I love fish! Here's a great site, if you're interested:
Aquarium Fish | Tropical Fish
Definitely don't try multiple bettas XD Multiple females can get along, but not in that small of a tank.
I find african dwarf frogs (I believe that's the kind of frog we're talking about) are hard to care for if you don't know what you're doing. They have poor eyesight and you have to spot-feed them; for this reason, it's best to keep them in species-only tanks as they can be out-competed for food.
In a 10 gallon, I'd try a small school of neon tetras or maybe harlequin rasboras, and maybe a gourami. You could also do a gourami, some pygmy or panda cories, and guppies- get all male if you don't want babies.
Edit: the one inch per gallon rule isn't an accurate tool for stocking.
You will need a filter and heater; I guess a light is optional, but I would get one. Make sure you know what the nitrogen cycle is
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