After you register by clicking the "register" button at the bottom of this form, you will receive an email (at the email address you used in the form). The email will have a confirmation link. When you click the confirmation link in the email, you will confirm your registration.
If the confirmation is successful, you will see a page on the site letting you know. Click the "login" link at the top right corner of the page to login using the account you just created.