How can you turn your hair green?

If your hair is blonde, you can buy green hair dye and dye it according to directions or get it done at a professional salon.

If your hair is darker, then you have to bleach it then add color to your hair. This can also be done at a salon.

If you are asking for like a way to turn your hair green by accident, if your hair is blonde and you leave chlorine in it too long, eventually your hair reacts and it turns green.