I should also add that if you have not received the activation email, you can have it resent as follows:
1) Click the "Sign in" link
2) Scroll down to the "Trouble signing in?" section
3) Type in the email address that you registered with and type in the letters visible in the security image.
4) Click the "Resend Credentials" button
The forum will send you an email with a new randomly generated password. Sign-in with this password and then you can change it once signed in by click the "Profile" link.