ok i tried the search button and with my connection its just too slow to find what I want. So anyways what I need is to know is how the hell i need to hook up my AF ratio guage

i bought it almost a year ago and i lost the install manual and theres 4 wires ..... red (Posative) , Black (Neg) , Green (???) and white ( i think it goes to the headlights so when u turn on the headlights the guage is back-lit), anyways im wondering just how to do this and what the green wire needs to connect to exactly, if anyone has any info it would be much appreciated, thanks.
Steve