enter your email address and whatever password you have.

If the reply on the page says
"That password was not found"
then use the password reminder tool to get it sent to you (it maybe a new password generated by the system, but you can change it once logged in)

If the reply is
"Your email address was not found - please join"
then you will need to join as a completely new member

if the page that returns says "click on the link in the confirmation email sent to your email address" then do that and it will confirm your email address

You may need to complete both of these processes:
1. get your password
2. confirm your email address