There are loads of problems with what you have posted. The most blatant issue is going to be how you have called your forms - there is one for every student. The second issue is you are creating an array `attendance`, but you don't fill it with anything unique to identify it on the processing side.
To answer some of your questions:
1) You put the submit button at the end of the form - wherever you want that to be.
2) Each student is going to have a value, look there
3) When you figure that out, it'll all make sense