I'm not a frog keeper, so my advice should be taken as such. I would imagine that a moss or orchid bark substate would keep the humidity you want. A good size waterbowl should be provided. Depending on the species you may need hides and perching areas. As for food, check the classifieds and see if you can find a fruitfly culture. They should be a good feeding size for it. Or you may get cricket nymphs (pinheads) but they grow fast and you would need to keep buying them. Maybe that'll help.