halo projector lights questions???

I recently bought a set of halo projector headlights for my 07 v6, they are going to fit perfect only problems are that I have to remove the front bumper to get the old lights out and new ones in. The low beam/high beam lights plug right in to the normal plug off the car, but the new lights have two white wires and two black wires off the back from the halo rings, the two black wires are suppose to connect to the negative of the running lights/blinker lights. Now which one of the wires that go to the r.l.'s is the negative one????
please help, the only thing i can think of is to use a tester light. but does anyone know?????