Okay, not too bad for a first time, but hopefully with this crit, you could improve next time. First things firsts, NEVER save in JPEG, it makes your picture look blurry and Jagged, try to save it on PNG so it won't ruin the quality. Now, on to the shading. The shading on the jobs and the fuzzy ball on the antenna are perfectly fine, it's the shading on the body that you need to work on. Now I'm glad that you chose a light source, but sadly, when you are shading, it can't look like it has random blotches/ stripes on it's body. The shading is supposed to blend with the other colors, and give it a more 3D-ish look. Finally, the proportion of the Kupo seem to be good except for the left foot (my left) which I beleive is slanted on the wrong way. Because of the way it is positioned, I think it would've been better if it would've been slanted on the opposite side, but that's an opinion which I'm not so sure about. Anyways to wrap it up, good start, now keep practicing.
PS: One last thing, when you draw a sketch in Paint, try to color it with a different color other then black. Then, once the sketch is doen, go over the outlines with the black color, and I'd advice you to use the Curve tool so it would be more flowy and smooth.
...but its the first time I shade anything...lol
