First of all, congratulations! Being accepted to a study means that the researchers want to hear from you, because you are the kind of person who knows the answers to the questions they want answered.
Every study is unique, and the study that you got accepted to will ask you some questions about the things you like, the things you don't like, and you'll get to explain why. After taking the "screener" survey and answering all the questions as honestly as you can, the researchers use your answers to determine whether or not you fall into the exact group that they want to hear from. If you're accepted, then you get to answer their questions, and upon completion, you get your $50.
So, if you've been accepted, we can't wait to hear from you!