All right!

Buy some food. Iguanas can eat crickets, mealworms, and friut flies. Porvide fresh water.

How big is he?

http://www.triciaswaterdragon.com/igcare.htm

Honestly, you should return the iguana and get a leopard gecko or bearded dragon. Iguanas are not a beginner species. You are going to need a HUGE custom built enclosure by the time the ig reaches 18 months (think large walk-in closet or small bedroom). They require hot basking areas, cool spots, hides, high humidity and plenty of climbing space. If absolutely necessary you can keep a hatchling ig in a 55g tank, but they need upgraded as soon as possible. Igs are total herbivores ~ no meat or animal products in their diets EVER. They need UV lighting and the tube needs to be replaced every 6 months. Basking lights, heat pads, large water dishes, etc. Once that lizard hits puberty his/her attitude will most likely change, especially during breeding season. They get extremely large, territorial (including w/ people) and can get aggressive.

If you insist on keeping the ig (and for the animal’s sake I truly hope and strongly suggest you don’t), start researching immediately. Go buy a copy of Melissa Kaplan’s “Iguana’s for Dummies”. Check out these sites ~

http://www.anapsid.org/iguana/index.html
http://www.greenigsociety.org/careinfo.htm
http://www.wnyherp.org/care-sheets/lizards/green-iguana.php
http://www.kingsnake.com/rockymountain/RMHPages/RMHgreen.htm

Igs are prone to a multitude of health issues, if you plan on keeping this lizard you need to find a good reptile vet immediately. Take the lizard in for an initial check-up and get to know your vet, you’ll be using them a lot.

Again, please consider exchanging the ig for a beginner species. Do some research into leopard geckos and bearded dragons. Your son can easily bond with both and they are much easier to care for.

Hey, you shouldn’t have bought it as they require expert care and 8-9 foot custom cage, but since you have him i’ll tell you how to care or them. The enclosure for an adult iguana is very large. The enclosure should be at least six feet tall, about 1½ to twice the length of the iguana, and 2/3 to one full length of the iguana wide. For a six foot adult iguana, this is an enclosure that is 9 to 12 feet long, four to six feet wide, and at least six feet tall. Sufficient branches and shelves for climbing and lounging should also be provided. To give you perspective on the size of the enclosure, most small bedrooms are only 9 feet wide. This is why many owners dedicate a separate room as their “iguana room.” Some owners also allow their iguanas to “free range” throughout the house. If you allow your iguana to live in its own room or free range, be sure the keep the area the iguana will frequent free of small objects that the iguana may accidentally ingest.

Iguanas come from a tropical climate and need to be kept warm. Daytime temperatures should be 80° – 85° F with a basking spot of 90° – 95° F. There should be a range of temperatures offered to the iguana to allow it to thermoregulate itself. Nighttime temperatures should be 75° – 80° F. All temperatures should be verified with a thermometer regularly.
Ultraviolet lighting providing UVA and UVB is required for proper calcium metabolism and skeletal development. Without the proper lighting your will become sick and die a very painful death. Proper lighting can be provided utilizing fluorescent tubes specially made for use by reptiles as well as mercury vapor bulbs that also provide some heat as well. Additional heat can be provided utilizing infrared ceramic emitters and incandescent basking bulbs. Hot rocks should never be used under any circumstance as they can severely burn your iguana.

Iguanas are strict herbivores. Many older literatures will suggest feeding animal protein or even cat food. While some wild iguanas may ingest the occasional insect while eating leaves, it is not a significant portion on their diet. Iguanas that are fed too much animal protein will develop health problems and will die prematurely. A well balanced iguana diet will consist of about 40% to 45% greens (this includes, but is not limited to collard greens, turnip greens, mustard greens, dandelion greens (with flowers), escarole, and/or water cress), 40% to 45% other vegetables (this includes but is not limited to green beans, orange-fleshed squashes (butternut, Kabocha), snap or snow peas, parsnip, asparagus, okra, alfalfa (mature, not sprouts), onions, mushrooms, bell peppers, sweet potato, zucchini, yellow squash, and/or carrots), 10% or less of fruits (including, but not limited to Figs (raw or dried), blackberries, strawberries, raspberries, grapes, mango, melon (cantaloupe, honeydew, watermelon), papaya, banana, and/or apple), and less than 5% of other grains or commercial diets. Iguanas should never be rhubarb as it is toxic. Certain lettuces such as iceberg, romaine, and Boston butter lack sufficient nutrients and should only be fed occasionally. Acidic fruits (citrus, tomatoes, kiwi, pineapples, etc.) should also be only fed occasionally as well. Tofu can be occasionally offered as well for supplemental protein, though if too much is given it can lead to long term health issues. Wild plants and flowers are not recommended since they may be toxic to your iguana or may contain pesticides that could be toxic as well.

Good luck.