Waaaay back in 1993, I downloadad an Amiga 'C' tutorial off of aminet. Very nice indeed and it was very well written. I only have a hardcopy of it now.
If you REALLY want to learn assembly, I have a book here called Amiga Machine Language. It was published by Abacus in 1990. It shows you intuition stuff like windows, event handling, requestors, etc and disk IO. Pretty dern nice book, BUT I would STRONGLY recommend that you experiment with 'C' first. I learned the basics of programming in 'C' and then kinda translated some things into ASM. Much easier that way

Of course, you may be a better programmer than I was back then, but with the 'C' code, it was easier to focus on the structures and stuff that was going on as opposed to having to learn structures AND fight 68000 Assembly at the same time.
-Thorrin