As common with most forums you need to validate your email address which helps us keep spammers out. You should receive an email either immediately or at most within a few minutes of registering, simply click the link in the email to 'validate' your account. You will not be able to post or do very much at all without validating your account.
I have manually validated two accounts I recognised from WOS however already.
If you do not appear to have an email: Please check your junk / spam email folders as its not unknown for it to end up in there in some cases. You can also click the 'resend validation' link on the very top right to send another email if required too. If you do not see this link and you're logged in then your account is validated already.