Why can't I participate on bitcointalk.org?
You should first make some posts on the Newbies forum. This post explains the restrictions.


  Newbie Restrictions You can only post in the Newbie and Local
  sub-forums till you have 5 posts and at least 4 hours on the forum. 
  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.