Change the Entire Page Layout

Hello Everyone
I am looking for someone that has completely modified their site to incorporate the shopping cart, just like some of the sites shown in the "Showcase" section. I want to incorporate this cart into my existing site.

Any suggestions on what is required for this? I have experience in coding ASP.NET using C#, and great experience with SQL database. I guess that I am not sure where the code is to accomplish this? is the page layout more of CSS? I have tried to back track thru the pages, beginning with default.aspx page to find where things like the queries or calls to the sprocs are located. I cannot find that thus far.

Is there a company that can modify this for me? I was thinking that I ran across one such company listing on here, for modifications, or completely new sites.

Thank you in advance for your help

Andrew SQLDBA

Contact me : www.strivingprogrammers.com