Once you have registered to post on these forums, your registration needs to be approved by the forum administrator or a moderator. This may take up to a day or so. Once approved, you'll be notified with a message sent to the e-mail address you entered when you registered. In that e-mail message is a link to complete the activation of your account.
If you don't receive an approval message within a reasonable time, check your "junk mail" or "spam" folder for the message. Many e-mail systems such as Hotmail will filter off messages from unknown e-mail addresses - like the one for the LIR forums.
If you still can't get things working send a message to
webmaster@lairdraceway.com. Include your name, the name you registered with, and the e-mail address you used when you registered.