Start a New League
You will be the commish of a private league. You can set league options and send league invitations.
Accept a League Invitation
If you expect to receive a league invitation from someone you know, you will be sent an email from the commish. You will also be able to accept the invitation here, when available.
Join an Open Public League
Join an open league and compete against other players on the web.
If you want to join a league with people you know, see 'Accept a League Invitation'.
Info about the leagues and how the league options work.