Hi almeras. It looks like they're running the compiled version. This makes sense because the application will run faster when compiled. Unfortunately, you won't be able to make changes to the source. You would have to download the source code version from nopCommerce. Open it in Visual Studio. Make your changes. Build the application. Upload to your web space. You would also need an instance of the database. Regards. Walter.
Not really. ASP.NET pages are always compiled. Any page which isn't precompiled gets compiled to a DLL on the first request and thereafter will load as quickly as a precompiled DLL.