Honda atv need to know which wires to headlight is positive and ground?

I have a honda atv and there's 3 wires that connect to it there's a green a blue and a white witch one is positive and which is ground

That's what I use a Digital Volt Meter to determine.

More then likely you have a high beam, so the middle wire on the light itself, if it's a sealed halogen, is ground and you should be able to guess what the other two do, high beam and regular

I would hook up a volt meter and find out.

Honda color codes -
Green = ground
White = headlight low beam
Blue = headlight high beam

Green & blue wires are your high and low beams, white is ground. You should get a volt meter to make sure though. If you connect the wrong wire to ground, mucho smoko.