How do you change hair colour on Adobe photoshop.com?

Most effective way is to go to: Layer > Adjustment Layer > Colour Layer (or something spelled like that, I think it's the last option) You can choose black for example (if your hair is black) and change the colours, you'll see what I mean. Sorry, all I can think of off the top of my head.

I suppose the easiest way to change hair color is to select the hair, cut it to a new layer, desaturate it, add a new layer above the hair, and add color using the overlay blending mode. You can change what a person is wearing, but it's a longer process.