How do you convert a YJ jeep Wrangler tail light to LED tail light?

I bought Peterson Manufacturing v420kr-5 led lights....they have tree wires Red goes to stop and turn, black goes to tail function, and white is ground. now my question is how can i convert this? i believe the yj stock wiring has no ground so how would i wire??? the yj harness has three wires also... how do i do this????? im so confused! i just look at the repair manual and got more confused!!!!!