There are a lot of places out there that will loan money to people with er, "challenged" credit. All you need to do is show you have a job, a bank account, and a couple of personal references.
Now, keep in mind you ARE going to pay huge interest rates. Most of the time, your payments are set up weekly. Be warned though, if you miss, or are late on even a single payment, you car will likely be gone with any down payment you may have put on it. And they usually require a substantial down payment.
There are many decent dealerships out there that will finance just about anyone, but you ARE going to pay through the nose, and the vehicle is going to be one that is way down the list of "desired" vehicles. Usually they are lease cars that have ton of miles on them for the year they are, trade-ins that better or higher class dealers do not want, etc. You are going to end up paying over twice what the vehicle is actually worth, or what someone with cash or good credit could walk up and buy it for.
Don't go to Big Ed's used cars for people who have bad credit, you know what I am talking about, the little car lot on the corner with a storage shed remodeled into a office. Unless you want a real piece of crap, for a ton of money, and a couple of broken legs if you miss a payement. There are a lot of larger respectable dealers who have programs for people with bad credit, find one them.