This is my iguana cage. There are many different kinds, but this is one I made for about 70.00. IT is 4' wide, 4'long, and goes all the way up to our 8' ceilings. It is made out of wood lattice which is VERY flimsy and has to be attached to a 1"x3" inch frame. The door has a 1.5' 'lip' at the bottom and I believe a 3' 'lip' at the top for stability. I also had to cut the screws flush so they wouldn't injure my igg. We had the 4' light strip laying around as well as a timer I set for a 12 hr cycle. Also attached to that 12 hr cycle is a UVB bulb but you can't see it in this picture. UVB bulbs are only effective at a distance up to 12 or 18" depending on the strength, so I gave my igg a couple weeks to find his favorite basking spot and then mounted it close to that spot.
Not ideal but probably the only way to go about delivering uvb to iggs in such a big cage.
Feed collard, mustard, and turnip greens like previously stated. For supplement, I like a good vitamin/mineral supplement WITHOUT d3. HOwever, my Igg has had a uvb his entire life, so yours should probably get a good d3 supplement for a while since it is unable to make it's own using the uvb bulb. (thats why iguanas die without it, uvb light allows them to synthesize their own vitamin D, which is essential in bone development.) After a while with a properly used uvb bulb, you shouldn't need to give d3 and in fact it can harm your igg if you do. Also to be noted, a UVB bulb is not effective through some screens and often has to be installed INSIDE of the cage.
A pelleted diet is ok as part of the diet. However, iguanas eat a lot of food generally every day. I give the above greens every day, along with green beans and carrots or squash, and soaked alfalfa pellets. He sometimes gets things fresh from the garden, and gets fruits 2x per week or so. I use fresh greens from Meijers (only place I can find it packaged and pre cut) and then get canned tropical veggies, fresh bananas, and the occasional strawberry. I mix them all the fruits together and then freeze them into baggies that last me the 2x per week feedings.