Ok so I have found everything I need on the business aspect to sell my product and have done so with success locally, but now I would like to try and expand a bit and create a website to attract a larger market. My problem is really I just dont know where to go to get the information I need to develop what I would like.

I am trying to develop a site with a drop down box similar to a few below, that allow my customers to put together there own computers and allows the site to change there total prices and output there build to me so that I can build it. So far until I get further in my development I would like to just do this on an EBAY account. Can someone show me how they did this and where I can go to get the information.

Ebay Example 1

Ebay Example 2

I have looked for the information but not sure on the termenology on what this is called so that I can do this myself.