FRC Docs
This is the official documentation for WPILib. If you want to become gigantic-minded, I highly suggest you just look through it and find things that interest you. If you’re not up to that, I compiled a list of pages which I think you should read.
Command-based programming At this point, you probably already know how to make subsystems and commands, and how to use them. I don’t think you really know what purpose they serve from a design standpoint. When reading these pages, please carefully read the text at the top. That’s the most important part of what they’re trying to say.
-
Note that you’ve only been working with JoystickButtons so far. Triggers are a much broader idea that when something happens, a command will run/stop. In your case, it has only been buttons being pressed, but now it can be readings on sensors, X seconds have passed in the game, or anything else that can be represented as a boolean.