I need a light - 1997 XR400R (kinda)

I just got this sucker and it took me quite a bit of money to get it back to normal and running. The people that had it before me had Frankensteined the shit out of other parts and I didn't know being kinda green to Hondas. I guess it tractors around purty good now, but at night I keep hitting shit pies and my dog loses track of me and it's only a matter of time before I squash him. One of the previous owners removed the light and discarded it (it's probably in the same shit heap that the tank, seat, petcock, fenders, various nuts and bolts, speedo, airbox, etc are in - what an asshole I was to buy this bike). Someone along the way installed a light switch, but the front is totally tabula rasa. Here's my question: I know absolutely zero about bike wiring. How do I know which LED light bar to buy that requires the right amount of Ws for the XR400? Which of these wires do I pull out and chop in? should be just earth and power once I have my W correct, right? Anyone know of a good guide to get me started? I'm striking out. I'll post pics of what I'm working with tonight.