READ THIS TOO!!!
It's taken a while to get around to but it's finally here.
It makes sense to me,but I've never done a tut before.So if you're feeling a bit lost,be free to give me a shout.
Basically for the Gradient at C.The light is striking the raised edge.So it's brightest there and goes down at a gradient until it blends to the colour of the helmet.
Also this might be usefull for gradients:[link]