Have a league credit? Here's how to use it to cover your signup fees!
During signup (after you receive an invite from your captain, or choose one of the signup options on the league info page), you'll be asked to sign in to you account.
On the details page, the very first option will ask you if you want to use your available credit. Just click the check box, and your credit will automatically be applied to your fees due on the payment page.
If you received a credit for a team in the past, it may not cover your fees completely in the future -- this is most likely because your new team is splitting the cost between fewer players than the team that received the credit.
Also, if your credit is more than the amount you owe, don't worry! The system will save your remaining credit for you to use the next time you sign up for one our leagues!