I’ll third this. As well as add: In particular, you’ll want to go through most of the “getting started” stuff, and the “Basics” section, then likely move on to the Command-Based section (not required to use Command Based, but its a pretty nice framework for organizing your robot code) under Advanced Programming. The JavaDocs are also linked on the site, as well as tons of examples to show practical application/methodology of the Command Based Framework.
Just know that there was a re-write of the Command Based Framework released for this season, so many 3-rd party resources haven’t caught up and will show examples/application of the older framework.
I agree with all above. If you go command based (which I heartily recommend), approach it like it was a high-level GUI toolkit, with commands tied to button clicks through descriptive calls, rather than trying to lever-and-stick the links between conditions and actions. No loops (except perhaps iterators over a limited set of objects) in your callback methods!