I see. And what should I do after I learned all about the form of aid I planned to take?
Then you should decide what aid you really need, and then respond to the school's aid offer within the deadline set by the school.
I have to send them those documents they requested, right?
Yes. All you need to do is provide the documentation your school asks for and be sure to do so by the school's deadline, or you won't be able to get financial aid.