I assume that you are just getting into digital art.
Just so you know everybody is not so good when first start out.
For this drawing, the line work is a little messy and the lighting does not make sense.
The posts on opposite sides have light coming from opposite direction and do not add up with the lighting on the character's face. Also, it appears that light is on top of the character's head.
I can see what you were going for but it came out a bit skewed.
If your were planning on having 4 light sources (from all directions) there wouldn't really be much shadow on the character, just on a few points.
Try to focus on one or two light sources, it will make it much easier.
Aside from that, the face and hair is drawn out pretty good.
Keep at it, you will get better.