Check your inbox
You should have two emails coming: the first is your "welcome" email, and the second is your "availability" email, which has specific instructions to complete the next step.
Read the "Welcome" email
The "welcome" email contains some important info that will help you get the most out of the classes, and is very worth reading once.
Read the "availability" email
Your "availability" email contains specific instructions on how to complete the next step, which is to submit your "availability", which we'll use to form the groups.
(in not-so-fine print!)