This app is generally based in the picture sell and purchase portal. You can simply register using facebook or creating account on it and start uploading pictures you click. This site also conducts some offers and missions. It gives you task of clicking a pic on a certain topic and the winner gets 100 us dollar. Also you can normally upload any pic and when someone want to purchase it. He/she will pay 5 dollar for per pic to foap and foap gives you 50% of that.
The idea is best and its really genuine. You can make payouts directly in your PayPal account.