That's great that he's active!
I've never had a moss ball so I have no idea if there is a certain way to take care of them, if any. What I do know is that there are really easy plants that don't need much extra care but the level of lighting they need. One of the best (in my opinion) is the anacharis plant. You can just let them float around or tether them to a rock and they're pretty much good to go. They grow baby anacharis that you can pick off and place somewhere else in the tank before it grows and grows. And apparently they are champs at eating up any ammonia in your water :)
PewPewPew has an amazing thread on plants in the Betta Fish Bowls, Habitats, and Accessories forum. You should def check that one out!!
Athena the Female Crowntail Betta
RIP Leo the Nerite Snail
Wishlist: Black Orchid CT
Tiger Nerite Snail