What is it like starting a car sales job?

im not doing a lot right now but the job i have is guaranteed pay. How does a sales job like this work, especially at first? will i get paid an hourly rate and a bonus if i help make a sale or how does that work. Do these people get fired easily if they're not great at sales. Its for nissan if that makes a difference. I would love to try something to get a career going but if i do this i will have no backup income. anyone did this? any help? thanks1