Looks like you're off to a good start. Also don't worry about you saying you dont know a lot and making your fish suffer. We all had to start somewhere, and the fact that you care enough to learn more shows that you are going to make a good fish parent, plus anything is better than what you find them in at the store!
Let me also say you really can't go wrong at all with any Seachem product. I use them in all five of my tanks. ( 3 Betta tanks, big planted tank, big reef tank) They're pretty amazing.
Might I suggest (If you aren't out of money! haha My sister kept on saying "all this for a $5 fish???" she just didn't get it then, but does now) that you might want to get Seachem's Stability. It does wonders for a quick, easy, and effective cycle. Plus I use it with every water change as well.
The best advice I've received in this hobby is, when you keep an aquarium all you are is a water keeper, the fish take care of themselves.Which translates into water quality is the key thing you concern yourself with and everything will be fine.
Now for a little opinion from me. Live plants are cheap, great for water quality, and look pretty. Put a lot of them in there, my bettas love swimming in the tall ones!
have fun and enjoy him, bettas have great personalities!