I wanna finance a car and I'm 18 with no credit what would I have too do?

Do you have a steady job or other means of repaying the loan if you are given one? Will another adult with good credit co-sign the loan for you? Are you buying a modest car at an average price? Otherwise, I would start by establishing a good record by having any bills like phones, power/water, cable, rent, and the like in your name and then, after about 6 months to a year, apply for a car loan (assuming you have paid your other bills on time).

Get a good paying full time job and keep it for a year or more. Bum rides or ride the bus in the meantime.