Help please!!!! i cant put my light up?

ok so one of my lights in my room went out so i tried to change it so i was Turing to figure out how to get this light off of my roof to change it and it just fell of and is now hanging by cords.... it looks like this one a href="http://www.lowes.com/pd_93188-17771-13215-1ROB_0__?productId=1266485&Ntt=flush+ceiling+lights&pl=1¤tURL=%2Fpl__0__s%3FNtt%3Dflush%2Bceiling%2Blights" rel="nofollow"http://www.lowes.com/pd_93188-17771-1321…/a and i cant put it back up please help and fast!!!!