I believe what you are asking for is how to create a forum in ASP.NET. If that is the case, there are a number of open-source forums out there that you can download and look through to see how they were built. Here is one example:
http://openforum.codeplex.com/[
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If you need specific advice on how to build your forum, we are going to need a better explanation of what you are trying to do. We will also need to see the code that you are stuck on.