Nice job with the shading and the colors on Spidey's outfit; unbelievable that you did this with either crayons or colored pencils. What exactly is going on in the background? I think there should be more shadows from behind and maybe fill in those white spots, unless you're trying to make it shiny. Good job on the scratches and bruises on him. It definitly tells you that Spidey has been in a rough fight. The spider should be more black than blue for it doesn't look quite right. Since Peter is from New York, where are the skyscrapers? I would give this an 8 out of 10.
#1) I used colored pencils, and there is no way that I can fill in those "white spots." Besides, they're actually patches of where I colored slightly lighter, not where I didn't color.
#2) I based this piece off of a reference image, and I think he was fighting in a warehouse or something. I'm as clueless as you are.
#3) Like I said in #2), I based it off a refernce image, and I couldn't tell what color it was, so I colored it black. When I found a different image, it was actually blue, so I edited it to make it blue.
#4) For a first time critiquing, you did a decent job.