Once you get accepted, your school will send you a proposed budget and financial aid offer. They'll tell you how much you need to borrow. Usually, you just pick a lender and sign some paperwork and your school takes care of the rest.
usually next the school will send you how much money you are approved for (tuition plus their estimate of cost of living) and a list of lenders. you choose a lender, the lender sends you promissory notes, you sign them and send them back, then lender sends your money to the school, the school takes thier cut, you get a check with what's left over, you go to the store and buy ramen noodles.