Hi NoFx,
http://wgt.com/invite4.aspx - For the gifting promotion you simply need to send a gift to non-wgt members by clicking GET STARTED. Choose an item in the pro shop and click GIVE AS GIFT. Click the radio button to enter an email address and enter the email address for your friend(s) that you are buying for.
Each of your friends will receive a referral link in their email and they must click the link at the bottom of the email to confirm they received the invite from you. Once they sign up for an account using your referral link you will receive a free pack of GI-D balls. If they don't click the link in the email there's no way for our system to know it came from you so be sure they use your referral link.
Hope that helps. =)