I could help.
hm. When you're going to shade your drawings you have to pick a certain spot on the page where you want your source of light to come in at.
like this:
the sun is on the right side in my point of view of the picture so. the light soure will come in at the right and your more shaded area will be on the left. (sorry the picture is a bit small)
I hope this helps out alittle Im not that great at explaining online. but you can find other websites that could explain further =) this is one of the basics of shading