Hello i think you should have an invitation system that auto adds you as the referrer if the click the link. And a link that you send to them and it adds your username auto to the referrer field. I think the link already exist just don't know what the url is.
For the sake of the contest, go into your User CP and look under the profile picture editing link - there should now be a link to click that will put your referral link in the URL bar of your browser. Copy/past that.
