If you are a SE&TRA member you can sign in by clicking on "Sign In" at the top of the page. Your SETRA ID (example S1234) is your user name and your AMA number as your password. You can change your password and password recovery question by clicking on My Account at the top of the page.
You must sign in to change your Harescramble rider number. You can take a look at your email address etc from the Membership Form link on the left once you sign in.