on the tail lights wiring, there are 3 wires
black (-)
green w/ white (+)
green w/ yellow (+)

Which one of these are for the high beam of the bulb, I want to connect some thing to my brake lights

Thanks

 

Not sure if I understand what you want to find. High beam bulb in the tail light, is that the one that lights up when you apply the brake?
Anyway my Haynes repair manual shows the rear combination lamp with the colors as follows(1995 ~ 1999):
Black (-)
Red/Blue (tail)
Red/Green (stop)
Green/Black (turn, left side)
Green/Yellow(turn, right side)