How to get rid of the black underarms?

i shave my hair or use a hair removal bt i neva wax , m 18 n my underarms are really very dark , i cant wear sleaveless n manny oder clothes which i wld want to.....cn u pleez help me out wid sumthin , is der any treatment which cn help me .....i want u get rid of it n tat too quick ....plzzz help