The reason you can't enter chat is because a user's first few posts need to be approved by staff. As you can imagine, we've had a higher workload since release, so sometimes it takes time. You have to just sit tight while that happens.
This question also doesn't belong in this section; the exact same one was asked a few days ago here, in the Site Feedback section. A tip for the future would be to look around a bit more before heading straight to the New Thread button, as chances are you'll find what you're looking for. So this is now getting locked, since I've answered questions.
Oh, and I merged your two previous threads into one.
