You may find this to be a good resource to help you get started: https://www.racedepartment.com/threads/assetto-corsa-faq-game-description.91105/
Anything not covered there, then feel free to ask either here or in the main Assetto thread. I don't want to throw too much at you right now
Right now, I'd say to just get set up and do some driving in whatever takes your fancy.
Great stuff. I'll get set up in the next day or two and get stuck in. Cheers.