When I try to register, I get the message "Please login as a registered user here, or specify a different email address"

This is possibly because you have already registered with us using this email address To resolve the problem, simply click on "Please click here to log in" and log in using your e-mail address and password. If you don’t know your password you can request a new one by clicking on the “Password Forgotten” link. Within a few minutes you will be sent a new temporary password. You will need to change this password the next time you log on.