You can only post in the Newbie and Local sub-forums till you have made one post and waited 4 hours. This post must be substantial: at least several sentences. The other two restrictions are you need 1 post to be able to send a PM and 10 posts to put a link in your sig.  You can only post once every 360 seconds to start and there are a few other things that trigger this timer such as logging in and searching.