Well, if you haven't noticed already,there are rooms set up. In order to get into these rooms, you must have a certain number of posts to get in. Once you have the amount of posts needed to gain access, just PM an administrator.
Here are the rooms along with the posts needed:
Penguin Club Penguins
100 posts
Penguin Club Kings
200 posts
Mysterious Penguin
1000 posts
Legendary Penguin
2200 posts