OMG!!! im not gonna freak. calm down camille :P ok. iguana care 101 first of all READ LIKE HELL. here are some sites that are GREAT and when i mean read i mean read EVERYTHING on there and join the iguana den forum their the best. heres the links there melissa kaplans site
http://www.anapsid.org theres the green iguana society site
http://www.greenigsociety.org and then theres iguana den
http://www.iguanaden.com and two books you should buy wich have good information and are considered the BIBLE of iguana care is Iguanas For Dummies bye Melissa Kaplan and green iguana- The ultimate owner’s Manual bye James W. Hatfield III. and no dont use undertank heaters he needs light from above and it has to be away from him so he doesent burn himself. preferable with screen mesh between them and he also needs a big habitat adleast 6 by 5 by 4 feet (when he gets full grown) if you do things right hell outgrow a 75 gallon tank in a year. for lettuce it has no nutritional value read the feeding info on iguana den because it would take forever for me to explain feeding. hell also need a uvb light suspended 6 to 8 inches from him when basking no more no less. hell need branches for climbing something to hide in. hell need daily baths (some even like the shower) for poty training and also for uvb lights it needs to be reptiglow 8.0 or reptisun 5.0. those are accepted uvb lights that are STRONG enough for iguanas. make shure you read those books and that site. iguanas are usually very hard to take care of. make shure you do the right things. if you have other questions you can ask me