The best solution that I recommend for you is to use ASP.NET MVC.
You could find a very good starting point on the next Microsoft site:
http://www.asp.net/mvc[
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Especially there are a set of 8 free training videos in the left area of the main page that I strongly recommend for learning ASP.NET MVC.
I have also a set of 4 articles about this subject, and here is the first one (the links to the others are in the article):
http://www.codeproject.com/Articles/Raul-Iloc#articles[
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