Unlocking forum after first post

[joshmv]

Hey everybody, I'm still pretty new to this, so I was wondering if someone could tell me how to install the mod where there is one public forum, and the other forums are only shown to people that have registered, and made a post.

Here is an example of what I'm talking about:

http://www.crackmuzik.com/forums/index.php?

You have to make a post in the "introduction" forum, before you can see the rest of the forum, which is actually really large in that example.

Sorry if that's a stupid question, just not sure where to track these things down yet.

Thanks!

Josh