They should be feed:
45% leafy greens such as escarole, dandelions, endive, mustard, and collards, NO lettuces or spinach! They aren't good for him.
45% hard mixed veggies such as an orange flesh squash the harder the better(acorn,pumpkin,butternut... fresh green beans, fresh peas, parsnip, and green bell peppers, NO broccoli or cauliflower, or avocado!
10% fruit such as figs, papaya, mango, pear, and berries. NO bananas, only very rarely as a treat.
NO ANIMAL PROTEIN such as bugs, meat, eggs, or cheese!
Temperature:
They need a basking area of 95-100 and normal temps of 75-85. NO heat rocks!
Lights:
They need a 5.0 UV light.
Hydration
They should also get baths everyday or so. And should have a water bowl in their cage.
Vet:
You should take Your Iguana for regular vet checkups to make sure it is in good health. Reptiles can have internal parasites that can harm them so you should make sure the vet checks that.
Here are some good sites, the first one was recomended by my vet.
If you have any other questions feel free to e-mail me.
http://www.anapsid.org/iguana/index.html
www.greenigsociety.org
www.triciaswaterdragon.com/igcare.htm
http://www.baskingspot.com/iguanas/igbook/
http://www.reptilecare.com/IgCare.htm