This tutorial will teach you how to digitally "dye" your hair, with the amazing Photoshop. This way is harmless and doesn't involve the use of chemicals of any sort.

OK, here is my starting image.

So open your picture up, now let's select our main tool for this tutorial, the "Lasso Tool [L]".

To color our image, we'll need to select only the hair part of the image. If you select any other part, that part will also be colored, which we don't want.

So move slowly and steadily along the hair line. Use Shift to select additional areas. This step may take a few minutes, but it's the most important part.

If you accidentally selected an area that you want to remove from the lasso selection.

OK, now you should have the perfect selection of the image's hair, like so:

Now that we have that, we need to actually color it. Go to Image >>> Adjustments >>> Hue/Saturation.

That will open a small window where you can define the color preferences of the new hair color. The easiest way to get your desired hair color is to play around with the bars until you get something you like.

On the bottom right, there's an option to select "Colorize", for this task, I would recommend that you don't use it, as if you select it, it will give you very un-natural colors to use, and we would probably like to color the hair with a "natural" color.

I chose a nice reddish color. Looks good, huh?

Hover over to see "before" image.

That came out very nice, you can choose whatever color you wish! My advice, try a few colors, see what looks best.