I'm new to the series as well and here's my experience so far (level 30ish):
You do quests to get XP and Zeni($$$).
-You gain levels which grant you attribute points. You get a set amount of attribute points that seem to increase at certain intervals (now i'm getting 5 per level up rather than 3 or 4). You can put it into Health, Ki, Stamina, Basic Attack, Strike Attack, and Ki Attack. The last two types seem to basically impact how your special attacks scale. Some use strike attack and some use ki. It's pretty obvious when you actually look at the icons and associate it with what the animation looks like. So you get a set amount of attribute points overall that you will put into those slots however you see fit. Basically, this is how you go about making a character build, by allocating the skill points in a certain way.
-You also "train" with a bunch of people. I think there are 32 trainers, and so far each trainer has given me a total of 4 different moves, 3 special moves and 1 super move or whatever it's called. So Krillin taught me destructo-disc whereas yamcha taught me how to play dead. Basically, there are a ton of different moves that you can freely choose from.
-Lastly, there are slots for gear that impact stats as well as "QQ bangs," which just seems like an accessory. They impact the same stats as the other stuff, so there's more room for customization on that end as well.
Hopefully I could help! I'm still pretty new myself, so I could be missing things.