Just to let you know a lot of places pull this.
Essentially what happens is after you get 10 random people to click on your "referral link", supposedly it opens up specific codes you can redeem in your game client or whatever else you're running.
What actually happens is after you get 10 referrals, you then go to the website where you are supposed to get a free code, but it's a survey they ask you to fill out instead. Filling out the survey gives the website money, often times puts spyware on your computer, and then you never receive a code. It's a pretty shady and sad way of trying to get money. With any online game or company, you'll run into these websites -a lot.-