You should really wait a bit longer and do a fishless cycle on the ten gallon before you add any fish. It is a very simple process that will save you a lot of time and effort in the long run. Take the time to research the Nitrogen Cycle and how to conduct a fishless cycle before you do anything else--you'll thank me later. :)
As for stocking, I usually recommend a school (6 or more individuals) of panda cories or pygmy cories for 10G tanks. These are small, cute, and very active bottom dwellers that won't bully your betta, and likely will not draw aggression from your betta. It's a good idea to put the cories in first, after your tank has cycled, of course--because the betta will be more likely to accept their presence if they're in there before he has had time to establish his territory and build/defend a bubblenest.
African Dwarf Frogs are good tankmates, too, but there is a big problem with keeping them with other fish. That problem is related to the way they eat. Frogs are almost completely blind and hunt their food by smell. The problem is that sight animals like fish find the frog's food before they even manage to get a whiff of it, so many frogs end up starving to death in these situations. When I had an ADF, I had to feed it by sticking my arm in the tank and waving a worm in front of his nose until he realized it was there and decided to chomp it. I enjoyed my frogs, but feeding him was so challenging that I don't think I will ever get more. If you're thinking of getting a frog, do your research. They are very sensitive animals that need a specific diet that is not necessarily composed of "frog pellets."