This is a very cool drawing. The character has a ton of personality and has a very strong silhouette. The shapes in the background also look really great and do a lot to complement the character and the pose he is in. All of which makes it very hard to have to grade this so low.
Your drawing is horribly represented here, it's at an angle, the paper isn't flush against a backing, there's a bunch of the background showing, the lighting isn't great and most of all its not properly oriented. These are all very simple to fix by just spending a bit more time on the picture. Retake the the pictures and be sure to crop it all out so that it is just the drawing and nothing else. Presentation is extremely important in showcasing art and if it's bad the viewer's opinion of your work will automatically have a cloud over it.