Important:  I am in the processing of switching to an open-source PHP-based shopping cart, so I will be updating this article sometime during 2011.  (PHP is a programming language.  Open-source means that the code is given freely to the public, and anyone with adequate knowledge can make changes to the code.)  Shopping cart programs are installed directly on your web server, whereas the Mal's e-Commerce cart that I recommend below uses Mal's own servers.  Shopping cart programs that you install on your web server generally have more features than Mal is able to provide.  Indeed, my new PHP shopping cart has proved to be far more flexible and is much easier to work with.

How to Install a Shopping Cart on Your Site
(This is the new article, not yet finished)

Overview

Having a shopping cart on your site will make it easier for your customers to make selections, and it will increase your sales.  Indeed, in this day and age, you can't make an online business work if you don't have a shopping cart.  I used to use a shopping cart service called Mal's e-Commerce (based in England).  It did the job, but its features were limited.  The actual shopping cart was on Mal's own servers, instead of on my own server (by "my own server" I mean the server provided for my use by my web-hosting company, which allows my site to be seen on the internet).  The way it worked was this:  I would insert "Buy Now" buttons on my site wherever I wanted a customer to be able to buy an item.  When the customer would click on the Buy Now button, she would be taken into the shopping cart (on Mal's server) where the item would be added to the cart.  Then, to continue shopping, she would press a "Continue Shopping" button which would take her back to my site.  When the customer was ready to check out, she would go to the cart (either by adding an item to the cart or by clicking a "Go to Cart" button).  That would take her back to the cart on Mal's server, and she would check out from there.

My new shopping cart (and the type that I now recommend to my customers) is a program that is installed directly on my own server (again, meaning the server provided for my use by my web-hosting company so that my site can be seen on the internet).  Both types of carts (i.e., carts that are installed on your site vs. the shopping-cart service's site) require a certain amount of technical knowledge, and there's the rub.  If you are technically "challenged", both types of carts will present a problem for you (although there will be directions for you to follow).  There is a third alternative which is more expensive but is better for the technically challenged:  e-commerce hosting services like Etsy and Ruby Lane.  Services like that (which are somewhat similar to eBay but aren't true auction sites) provide everything you need to set up your site without your having to have any technical knowledge.  However, they also charge substantial fees, and they take a percentage of your sales (just like eBay does).  My recommendation is that you go with your own shopping cart on your own site.  That way, your business can be found under its own domain name.

For the technically challenged, let me say that installing a shopping cart program directly on your own site doesn't have to require technical knowledge, especially since you'll be following directions.  The problem is this:  Once you install the cart, you will want to customize it, and customizing it will probably require you to modify the code.  If the shopping cart that you choose is a well-designed, fully featured cart, then the amount of customizing you will have to do will be minimal.  But it is a rare merchant who doesn't want to make change that exceed what the set-up options allow you to do.

Let me give you some examples.  The shopping cart that I installed on my site is called OpenCart.  It is a fairly new program which lacks some features found in older carts, but I chose it because the interface is clean and the code (I have heard) is also clean (clean code means that it runs fast and is less likely to crash).  In the administrative portion of the site, it allows me to specify how many items I want to display per page; so to change that parameter requires no technical knowledge.  However, I also wanted to change the number of product columns per page (from 4 to 3), and I wanted to change the color of the bar at the top, and I wanted to change the word "basket" to "cart" throughout, and I wanted to make the section headings initial caps instead of all caps.  Making all of those changes required that I make changes to the code.  I had help, of course; I posted questions in the company's forum asking them how to do it.  Since the shopping cart is free, they have no obligation to answer such questions, but I usually got answers.  When you go into the code, you have to be very careful about what you do.  Accidentally erasing a bracket or a comma or a period can cause the cart to malfunction.

It's not my intention to scare you off of installing your own cart.  I believe that any intelligent person can do it.  However, if you are not already knowledgeable about computers, or if you find anything technical daunting, the learning curve will be steeper for you.

Finding a cart

First, let me mention that every shopping has an administrative area where you set the features that you want.  It is also in the administrative area that you will enter new products and find the orders that customers place.

The next step is to decide which shopping cart you want.  The way to do that is to search the internet for shopping cart programs and for reviews of shopping cart programs.  Unfortunately, you'll find precious little in the way of reviews.  Once you find the different programs, you'll want to visit the web site of the company that makes the cart.  Every site will have a demo cart which you can try out (as part of the demo cart, you should be able to see the administrative area).  I went with OpenCart partly because I liked their demo site, but partly because many of the comments on a page that I visited indicated that the code of OpenCart was "clean", and that the program worked fast.  This is the page I visited:

http://webtecker.com/2008/04/22/8-best-open-source-shopping-cart-solutions/

Once you have selected your shopping cart program, there is little else for me to say here that can help you.  The shopping cart program will come with installation instructions -- but installing a program on your hosting server is a more complicated process than installing a program on your computer.  You will have to go to the control panel for your remote web site.

How to Install a Shopping Cart on Your Site
(This is the old article)

Having a shopping cart on your site will make it easier for your customers to make selections, and it will increase your sales.  I have used only one shopping cart, and although it has limitations, it is cheap and workable, so I thought I would share my experience for the benefit of my customers (is that a run-on sentence or what?).  Although I am recommending just this particular shopping cart service, I assure you that this is not an advertisement.  I haven't been paid for saying any of these things.

There are three basic ways to get a shopping cart:

1.  Purchase a shopping cart program.  Shopping cart programs can be quite expensive.  In addition, you have to install the program on your server, and your hosting company may not permit that.

2.  Move your site to a hosting company that offers an "e-commerce" plan with a shopping cart.  This is certainly a good option.  E-commerce hosting plans that offer a shopping cart program (such as Miva Merchant or osCommerce) used to be expensive, but prices have come down.  However, there is a disadvantage to this option:  the shopping cart that you get with your hosting plan isn't portable to other hosting companies.  If you decide to move your site to another hosting company, you will have to re-do your cart at the new company.  (I have never done this myself, so I don't know how much work is involved.)

3.  Use a free shopping cart service.  Believe it or not, it is possible to get a shopping cart for your site that costs no money at all.  The one that I am using is by Mal Stewart at www.mals-e.com (his company is called "Mal's e-Commerce").  Mal has a free shopping-cart service and a Premium service that costs $8 per month.  The free service can be hooked up to PayPal, which will enable you to accept payments in real time (i.e., at the time of sale).  The Premium cart has more features and can be hooked up to a merchant account.  Mal offers his free service in the hope that you will eventually upgrade to his Premium service, and I am sure that many of his customers do, as I did.

Another advantage of Mal's cart is that it has excellent portability.  If you change hosting companies, you do not have to set up your cart again at the new company – no work at all has to be done to move the cart.

Here is how it works:

► When you apply for Mal's service, you will be assigned a user name and password that will give you access to the shopping cart program on Mal's server.  (The shopping cart actually exists on Mal's server, not on yours.)  You customize and manage your shopping cart by logging into Mal's "Admin" area.

► On Mal's site you will find the HTML code for "Add to Cart" and "Go to Cart" links, which you will insert alongside the products on your site.  Those links can be either text or buttons.  (Note:  A rudimentary understanding of HTML is needed; you will have to customize the links for your merchandise.)

► When your customer wants to buy an item, she will click on the "Add to Cart" link next to the product.  That will take her to the cart on Mal's server, where the item will be listed.  To keep shopping, she will click on the "Continue Shopping" button, which will take her back to your site.

► When your customer is ready to check out, she will go to the cart and click on "Go to Payments" (in my cart it says "Go to Checkout").  That will take her to an area where she will give you her shipping information.  When she submits the order, the order and shipping information will be e-mailed to you from the shopping cart and you can then contact her to arrange payment.  Mal's free shopping cart comes with a basic shipping calculator.

► If you want your customers to pay immediately, you can hook your shopping cart up to PayPal.  If your customer selects PayPal as the payment option, she will be transferred to PayPal's site.  PayPal will then take the payment and put it in your PayPal account.  You will then get e-mails from both the shopping cart and PayPal letting you know that you made a sale.  PayPal's standard service has some minor drawbacks, but basically it works very well.  You can also add Google Checkout to your free shopping cart.

► If you are not happy with PayPal's Standard service, you can upgrade to a real merchant account or to PayPal Payments Pro, which functions like a real merchant account.  To do so, you must upgrade to Mal's $8-per-month Premium service.  (Please note that Mal doesn't provide merchant accounts or other payment options himself; he just provides the cart.)  Mal's Premium shopping cart has more features, including a more advanced shipping calculator and a shipping calculator for both U.S. Postal and UPS rates.

Drawbacks of using Mal's shopping cart

Inadequate support.  Mal's business is apparently a sole proprietorship, meaning that Mal is the whole business.  There is nothing wrong with that – my business is also a sole proprietorship.  However, in order to be profitable, Mal needs to have thousands of customers, only some of whom are paying him a monthly fee.  Fielding questions from all those customers is a lot of work, and my experience is that Mal doesn't always answer his emails.

Confusing shipping calculator.  The shipping calculators that Mal uses – both the one with the free service and the one with the Premium service – are extremely complicated.  However, once you understand it, it works well.

Shopping cart timeout.  If a customer who is using your shopping cart doesn't access the cart for 90 minutes or more, her order will be erased.  This is an improvement over the old timeout, which was 30 minutes.  Nonetheless, I get occasional irate emails from customers who, while constructing their orders, decided to go to lunch and found their orders erased when they returned.  Many modern shopping cart programs give customers the option to save their orders for days, but this feature isn't available from Mal at this time.

No pictures.  You cannot insert thumbnail pictures of your products in the cart.

About PayPal's shopping cart:  PayPal has its own shopping cart which is free to Premier PayPal members.  It takes PayPal payments and credit-card payments from non-PayPal members, and I believe (though I'm not sure) that it gives customers the option to mail a check or money order.  PayPal customers who have allowed their accounts to lapse, or who have reached one of PayPal's "sending limits", or who are having some problem with their PayPal account and cannot use it, may have problems paying with a credit card – and that may be a very sizable group.

I have provided the information in this article simply to be helpful.  I used Mal's free service for a year before upgrading to his Premium service, and I was mostly happy with it.  Mal's shopping-cart service isn't the only one available, but I am not familiar with the others.  The only other shopping-cart service I looked at was much more expensive.