You bought the XTC lightbar, yes?
469k pdf
install guide.
BTW, that's also the best how-to on wiring pretty much any roof light on the front of the truck. Shows how to get from the roof, through the marker light boot, down the A-pillar, etc.
I've never wired rear lights on a full body H2 but imagine it would be pretty easy to run the rear light wires forward in the roof bar channel, then inside using the same path as the fronts.