I could be wrong because I haven't used this offer yet but I believe that you purchase the amount for example the fandango card at $21 and then a specific amount is credited back to your credit card at a certain time a couple months later.
To unlock more offers such as the other gift cards, it takes more people "checking in" to unlock them as the day goes by from what I understand.
If someone reserves a gift card but does not purchase within the next 3 days, a $10 reservation fee is charged and your account is locked until paid.