1) Sign up at Apple FreebieJeebies.
The only details you give when registering at this site is your name, email and address.
2) Complete one of the offers shown.
There are about 40 offers to choose from at the moment, and new ones are added regularly, so take some time to see which one suits you the most. There is more information on the various offers here.
3) Refer friends to sign up after you.
You will get a referral link when you sign up to Apple FreebieJeebies. This is the link your friends and family must use when they sign up because it tells the people at Apple FreebieJeebies that you are the referrer.