Here are the five most important elements of a tank setup:

Substrate
This can be some sort of dirt product, such as 'bed-a-beast' or potting soil. Be sure that if you use soil that there are no fertilizers or pesticides. Be absolutely sure that you DO NOT use gravel or a reptile bark that your frog could accidentally swallow! The substrate (of whatever type you choose) can then have a layer of moss on top to help prevent him from getting dirty.

Water Area
It is vital to have a water area for you frog to rehydrate himself! This should not be too deep (Tree Frogs are not great swimmers), but it should be deep enough that he can spread out in it and have all of his legs covered.

Shelter/Hiding
Your frog will thank you if you provide him with somewhere to hide during the day when he sleeps. This can be as simple as a piece of curled cork bark leaning against one side of your tank.

Temperature/Humidity
Day temps: 80s, Night temps: 70s. If heat is not coming from the temperature of the room, then it should be done from a top light source such as a heat lamp and not an under tank heater. Humidity can remain relatively low as long as there is a water dish to soak in. Mist once a week if you think it gets dry in your tank quickly.

Background
This isn't as important as some of the other stuff; but again, you'll have a happier frog if you put a background on at least 2 sides (preferably 3) of your tank. This can be as simple as dark construction paper or you can put fish tank backing scenery on it (which I think looks very nice).

N.B. This is the common set up for green and white's tree frogs. For other types please see the forum.

from Shanna