Once logged in you'll be taken to the offers page where you can earn virtual points redeemable at Paytoshi or FaucetBox. If you do not have a bitcoin wallet then you should start here: Getting Started With Bitcoin.
For the moment there are two ways for you to earn rewards. Once you are logged in you will be presented with an "Offer Wall" where you can choose to either install apps, or you can choose to complete some offers. Some offers require as little as an email address to earn rewards; and some of those provide even additional rewards like gift cards!
The referral system yields 50% rewards. You will automatically collect 50% of any rewards redeemed by members who use your referral link. They only have to follow your link once and it will be permantly attached to their account. However, if they've already followed a different referral link then yours will not replace it.