We have had this question asked many times, and mabey we should put something on the FAQ about it.
The teams hold try-outs at different times depending on what that team leaders policy. At this time, I believe all teams are full. Individual team leaders will post next try-out dates.
Actually theres a pinned post on this forum which is a wiating list. Just sign up there and you will be put on a team when theres space. You will be put on immediately if we know you, after a tryout if we dont. This is more to measure character than skill though.