You have 10 full attempts to try to log in before your account is locked. To unlock,
1. Check your email for an email with the subject line "Unlock Instructions".
2. Follow the instructions in the email you received by clicking the "Unlock my account" link and set a new password.
3. If you did not get the email, you can still unlock your account by requesting a password reset email on the login page (see screenshot below) and following the instructions in the password reset email.