How to place a .png texture with transparency over a material I am trying to create a low poly face with a face from a .png file. The issue is I already have material placed for hair and skin, as shown in the picture below. 

I have created a .png file with a face which I would like to overlay over the skin material on the front of the head.



All examples I searched so far assume I also want the color of the material from the .png texture.

Update:

I added UVMapping, changed view to texture, made sure one face is on the eye but nothing is displayed..... see image... I don't know what is going on.
The image texture node has two outputs, the color data and the alpha (transparency channel) data of the image.  The color data only holds the red, green, and blue of each pixel.  So if you plug it into a shader's color you will probably just get black where there is supposed to to transparency because those pixels are really black, but invisible.  You need to use the alpha output as a mask for placing the face over the skin shader.

To do this take whatever shaders you are using for the blank skin and mix them with a diffuse (or whatever other shader[s] you want for the facial features) based on the alpha output of the image texture.