CPAlead , adshiftmedia , CPAWay Postback API

Please do not bid if you don't know what CPAlead adshiftmedia cpaway is. I purchased a website script PPD and i want to learn how it work i simply just want to know how postback works. The site is about Paid/Pay per download my website [login to view URL] Script information : Registered users earn money when someone download their file after completing free survey. To complete survey there is no need to register here a demo page [login to view URL] Please only big if you can teach me how the system works so i can create my own script with it like user earn point after completing survey etc. and please create a small project for me to understand properly only basic login to upload file and automatic generate a download page with survey added with cpalead adshiftmedia or cpaway [login to view URL] also before doing this create a page that will fetch all offers from the api link (rss) to database. you can teach me on skype or create some tutorials or whatever you prefer