Hey, new Rock-and-Stoner here, any tips?

I would ideally like a bit about how the game works, how the different classes work, the enemies one might encounter, etc.

Maybe even a lore dump. Literally anything that will help me understand and enjoy the game! Thanks in advance btw.

I am especially interested in learning how each class works, what their job is, and how best to play them.

Also who is Karl in the “For Karl!” user flair?