duplicate the image then select the areas you want to tint with the polygonal lasso tool on the new layer you just made you can give them a tint by selecting the brush tool and lowering the opacity to about 30% you can give them a tint, then in the layers box where it says normal you can play about with options such as overlay and multiply, different ones give you a different effect, as it dows with how high or low the opacity of the tint