Just do tons of research and start practicing with something. rF features many different filesystems and you will need a lot of different programs to do a whole car or track from scratch.
You could start with opening different files the cars have with notepad and start figuring out how things work in rF. If you modify something make backups.
It will take tons of hours to learn enough to do a whole car properly. I don't think there is a tutorial what includes the whole lot, I think there even is multiple ways of doing different stuff.