Fresh, clean water needs to be available at all times. The same places that sell terrarium supplies carry an assortment of perfect water dishes and ‘wading pools’ for frogs. Buy at least two, so that a clean one can be in the terrarium while the other one is being washed. A bottle of water conditioner is useful for neutralizing some of the common chemicals in tap water.
Generally speaking, frogs are carnivores (meat-eaters) that eat their food while it is still alive. Crickets, various types of worms, caterpillars, moths, and fly larvae are all standard fare. Some of the larger frogs also eat mice, other frogs, and fish. For some species of frog, the rule is: “If it is alive and fits in the mouth, it is lunch”. Many pet stores sell worms, crickets, and so on. They can usually also provide the enclosures, substrates, and food for these creatures.