I got a pell grant & a sem. scholarship i start 8/15..how does a pell grant work? ?

Just wanna knw how it all works....I knw my classes are paid for by the scholarship...so now all I worry about is my books and supplies...I knw I can use pell grant for my books....but in the end does school keep remainder of grant or will I get it? And if I get it whenshould I get it?