I'm not aware of any specific examples, but I recommend you buy a book on the subject (or do some searches on Google/Code Project). Nobody here is not going to provide you with code tailored specifically to you. We'd just be searching online ourselves, so you might as well do this yourself.
With ASP.NET and SQL Server 2005, SQL would be your data layer (and you could build a data access later on top of that), ASP.NET would be your presentation layer, and you would also have to build a business logic layer. Here is a pretty good diagram of a typical 3-tier architecture:
Wikipedia diagram. Read more
here.