First, Merlin has given you a link to a good thermometer/hygrometer, you must get that very soon to know that the temperature and humidity are correct, first you must know the temperature is not too low or too high so they can digest food properly and be healthy. Yes, they will need some humidity, but not tropical conditions, in cooler season the temperature is lower, humidity is higher, but basically, they live in hot, dry areas, at some time during the year you can lower the temperature just like it is in the wild. I see websites which give different information for the same animals, it is difficult sometimes to choose the best, they DO live on sand in the wild, it IS o.k to use this in captivity without problems, if it is too dry then lightly spray, but not too much. You only need a shallow bowl of water, not too deep. Yes, you should offer food for them, crickets are o.k, roaches are excellent, locusts etc, a variety of insects. Do NOT leave crickets in the enclosure through the night, they can start to eat pieces from the lizards when they are sleeping.