Xprofile Fields in Registration in Buddypress 1.7

SO Buddypress 1.7 doesn't integrate xprofile fields into the registration page like previous Buddypress versions did. This thread below says to add a hook to the registration page but #1: where is the registratin page? I can't find register.php but my registration page is showing up.

http://wordpress.org/support/topic/birthdate-not-showing?replies=6