During the registration process, you should select the "Create Custom League" option only if you want to be commissioner of a Custom League and you plan on inviting managers to join your league.

If you simply want to create a team and join a league, you should follow the steps to join an existing league and then select the Public or Custom league option.

If you create a league using your Yahoo! ID and nobody joins that league, your league will not draft and you cannot participate in Fantasy Hockey using that team/league.