What's wrong with this iguana? Pics?

My aunt just gave me this iguana, it was my cousins. It has a dark patch in it's skin, and it looks like its also shedding in that area. I don't know what caused it. my aunt told me when they purchased it that it was a tiny little patch the size of a it's eye- for example, and now it's spreading. they gave it to me because they know i love animals (cats & dogs) but i've never dealt with reptiles. What can I do, or what could it be? Is it because of a uvb problem? They didn't give me any lights or anything, so maybe that's whats causing this? or is it just a common shedding problem? All they gave me was a terrarium. It's a very active little iggy, and has a great appetite…also scared and a bit aggressive, though. Help me, please! I want to help bring it back to health and properly care for it. Here are the pictures:

This one was taken today, I gave it a bath:

http://s986.photobucket0o0com/albums/ae345/blackdahliashort/?action=view&current=101_1217.jpg

this one was taken about 2 days ago:

http://s986.photobucket0o0com/albums/ae345/blackdahliashort/?action=view&current=101_1018.jpg

Also, I've done research on their diet…but I'd like to know what the best foods would be? Thanks so much in advace.