Get an under tank heat mat. Get one that is 1/3 the size of the tank. It is hard to keep temps right in a tank but if you use a UTH along with the lamps it should be fine. Just be sure you pick up a thermostat to plug the heat mat into so you can control how hot it gets.
To help the humidity just cover most of the top of the screen with something. I used towels when I had tanks. People use plexiglass, foil, duct tape (only on the top so the snake cant get stuck in it). Only leave enough of a gap for the lights.