Hello,
I do not understand how you can fork out $1600 and not know a thing about it? It boggles my imagination...enough said on that. If the picture you depict is the animal in question, that is a green Iguana (Iguana iguana), from central/south America.
If you purchased a green tree monitor, aka Emerald monitor, Varanus prasinus, then you have indeed bought a beautiful animal. This species is indegenous to Papua New Guinea, and surrounding islands...this species lives in lowland rainforests, in both primary and secondary forests, riparian habitats, and foothill forests.
It is often found in and around Pandanus foliage (= screw pine plants), where it can also find one of its most staple food items: walking sticks (Phasmids) amd Katydid insects = this is primarily a bug eater monitor, so offer it crickets, grasshoppers, insects of all kinds (it may not eat beetles), and see if its dietary intake increases? If not also offer it small pinkie mice, newborn types and dust the whole lot with calcium. Offer live prey. Put some orange, banana, cactus, etc fruit into the enclosure so the bugs have something to eat other than the monitor which they could chew on! Or remove them when you're satisfied it won't eat. Leave the lizard alone as much as possible for first month or so so it can acclimate and get used to its surroundings; add alot of live, plastic etc plants to the enclosure, some cork bark labyrinths so they have somewhere to hide and feel secure. Keep the humidity high, but overall temp does not need to be more than 90F.
Good Luck,
mbayless