Hey hello @phil, I gave a try at explaining what a template is. Maybe it eventually turns out useful for other people as well.
I did it in another thread, because it seems a bit dettached from the initial question, and it may be useful to people not using the Learn4 theme as well.
Here is the explanation.
I tried to make it as graphic and simple as possible, but I hope you can realize that it took me more than two hours to write that post, so what you’re asking: “full tutorials on how to use grav” is extremely time consuming to write. I did it because I hope it can be useful to many. But it’s not a light request you have to this community to answer questions in such a broad way.
Anyway, I hope it helps and clarify some things.