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You need to fill the tank with water so if they stand on their back legs their noses can poke out of the water to breathe.
They can live in coldwater or warmwater and seem to prefer warmwater. You need to put a chemical in that takes the chlorine and things out of the water, or you can leave the amount of water to stand for 24 hours before putting your frogs in it (the chlorine etc will evaporate out of it).
You need to do frequent water changes, but again leaving the water to stand for 24 hours or using a chemical to rid the water of chlorines and other chemicals toxic to the frogs. I would personally stand the water for 24 hours, I do that for all my tanks.
I don't know about feeding Dwarf African Clawed Frogs but the Normal clawed frogs will eat bloodworm, crickets, small fish, mealworms, waxworms, anything they can get to, I've had mine eat veggies! You can overfeed them though, so if you notice they're abit to fat, reduce the intake. Obviously a Dwarf Clawed will eat much smaller food.
I think you should start with African clawed frogs before working with the dwarfs IMO.