Let me put this straight, I have NEVER attended to any art related classes, and tbh, I'm sure I can do better than this. Of course, if you are not familiar with digital art, then it can be confusing for some time. My suggestion is to make a drawing, then scan it, and make a digital drawing out of it. I'm sure this will help you understanding better how to draw with a mouse. One thing I find weird is that even if you're new to this, you should've learned in your art classes that your drawings needs shading if you don't want them too look flat :?