You basically need a decent DB structure in place before you start coding the forums. Think about how TheScripts is laid out, and how you would go about applying techniques that you see in use here - things like user logins, threads, forum groups, DHTML menus (probably dynamically generated, too), user profiles, private messaging and message tracking (which is fairly impressive for a forum!).
You might also want to consider RSS as this is a very popular feature now - to subscribe to a thread that you're actively interested in using RSS, and then your newsreader automatically notifies you of any new items that appear in the RSS feed.
There are some free ASP forums you can download but the best free forum software isn't in ASP, it's in PHP - things like phpBB or inVision. Allows user skinning, built-in user management and all powered by a MySQL DB. (And that's coming from a hardcore ASP developer... lol).
I would normally offer bits of code for a small issue but you need a lot of code which is probably beyond the scope of what people offer in terms of advice (I've never seen a developer on this site offer up their services totally gratis for a major chunk of a project). Maybe stick a post in the Jobs section if you need it done quickly? If you get a decent developer, they may even show you how they've coded the features so you can then learn the techniques that you will find useful yourself later in commercial programming life, and this also gives you a good grounding in supporting the forums from an administrative technical perspective should anything go wrong.
Good luck!
medicineworker