50-70 percent humidity is fine for the WTFs. Above that is usually too much.
Room temps are usually fine also. 68 to 70 nighttime and 75-78 daytime. A basic compact florescent is enough t make both a temp change and day/night cycle.

As Martin stated above, sphagnum moss is great for keeping moisture in the tank but can be a potential impaction hazard since Whites will swallow anything that hits their mouth when diving for a cricket.
Digestible substrate such as Eco Earth, Plantation Soil, or Coco Fiber is usually the best choice for a Whites Tree Frog.


Hope this helps.