now extrac the helmet from the original image and desaturate it. the put it on above all layers. give an overlay with 100 %. to the previous layes make a layer mask. and start erasing with different opacities.
open the masai image and put it lower of the helmet layers. with transform tool adjust the size and center it so you can see the eyes through the openings of the helmet. keep usin layer mask to show how much you want to be seen of the man behind the helmet