It is generally not a good idea to keep different species in the same enclosure together, especially one so small.
This is particularly true with amphibians, as they absorb oxygen and water through their skin and as such are very sensitive to their environment. Many species also secrete toxins from their skins that may harm the other inhabitants.
Another reason not to keep 'em together: Frogs are carnivorous, and it is not unusual for a frog to eat a smaller frog, especially if it is another species.
Also, many of these animals are native to different parts of the world from each other, and therefore their ideal environments cannot be duplicated within the same tank. They may require different humidity, diet, substrate, heat, etc.
Your animals will thrive if they are kept in separate enclosures, especially if they are sized appropriately and given the correct habitat and diet. Good luck-do LOTS of research before you get any animals, make sure you have everything they need and their tank has been set up for a few weeks so the specs are right, and have fun, you'll do well!