Light & Shadow part 1

This is very very basic, we first take a look at the eye socket and cheek area. This is going to just look at the human face in planes, such as flat and raised surfaces.
If you look at image 4, as you can see I've made my 'socket' using flat lines rather than how it should look with curves. This is how I go through sorting out the shadows in my images. With out the eye ball imagine the inside of the socket are two separate areas. So depending on how little 'light' there will be will depend on how much of the eye area you cover. The lined area is where the light would be hitting the area.
I know my explanation sucks, I really hope the illustrations help even a little. I will be adding the whole face front and profile view. If it doesn't make sense in any way (I'm sure it doesn't) just let me know.