Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Sign-ups go up a month after the last round. I don't know the exact date, but it should be soonish. Just sign-up when you see the thread (make sure to sign-up early) and you'll likely get a tutor if one is available for you.