I want to know what i need to be approved i want
to get a used car an trade in my old one
You will need to show proof of employment. They will do a credit check to see if you are a good fit for that said vehicle and a reliable person, etc.
My suggestion is to shop around. You should get at least 3 quotes from different places to see which one is best suited for you and your financial obligations. Once you sign a contract it's binding and extremely hard to get out of.