Core Mechanics
If "rules-light" is your game, you've probably seen enough at this point to improvise your way through, but there's lots more to learn.
A lot of the time you won't need any "mechanics" at all. You've built an interesting character with motivations and talents, and until you try something where success is uncertain and failure has meaningful consequences you can soar through the story on tasty snacks and tabletop banter… but sooner or later you're probably going to want the dice.