Need help installing outlets.?

ok you guys have helped me out a lot so far so i think this should be my last question. I'm finishing a room in my basement and it currently has no outlets. there are two light fixtures in the room. i unscrewed one of the fixtures and found two black wires screwed to the backside. i cant tell which one of the wires is positive or negative. all i can see on the two wires is, rome cable 12wag and 600v. how do i go about wiring this power source from the light fixture into a few outlets? what type of wire would i need? any particular outlets i should buy? And how would i go about adding a light switch to the room? the way the lights are turned on now is just by screwing or unscrewing the light bulb.