Now we have to apply an adjustment layerabove the image. Click on the icon which circled in red in the image and choose HUe/Saturation from the menu. I want give red highlights to the hairs. NOw click on colorise and apply the following settings:
Hue = 2
Saturation = 58
Lightness = -41


These values can be varied to change the hair colour to individual tastes.

Now fill black colour in the masking layer indicated in red circle in the image and start painting on the parts of the image you want to colour with white colour and soft brush in the masking layer. You can alter the size and softness of the brush according to your requirement.

In this step I have completed the highlighting. Here I have also coloured the eyes and the eyelids a bit.

Here is the final result....
Hope this tutorial was helpful to you....