Welcome to fish keeping! Frogs are a great, low maintenence addition. I always love adding a new type of animal to my collection. Dwarf frogs and clawed frogs are "cousins" but not very similar. Sometime Clawed frogs are mislabled as dwarf frogs when they are young. Young clawed frogs and dwarf frogs have one distince difference: dwarf frogs have webbing on their front feet whereas clawed don't.
A five gallon tank is the perfect place to start with frogs. This suits 1 African Clawed Frog, but many more dwarf. I'd say about 6 dwarf frogs in a frog only tank. I recommend, for a more interesting look, to add either 2 frogs and 1 betta, or 2 frogs and a small school of neon tetras.
I'm not sure what African Clawed Frogs eat, but Dwarf frogs will eat a variety of things. They will accept bloodworms, shrimp pellets*, or any aquatic frog pellet. If the pellets are larger than this " they should be broken or crumbled, since Dwarf Frogs can easily be killed by a too large pellet causing intestinal blockage.
Dwarf Frogs are usually a little over $1 and I would recommend them over the clawed frogs for your tank.