how do i get my iphone5 to sync with my cars handsfree bluetooth?

Put the car in discover mode, go to bluetoth in the iphone and select it

You need to check the car's manual to see how to put the car into discovery/pairing mode. Once that is done, the iPhone and car should recognize each other, so long as Bluetooth is turned on in the phone. You may have to enter a passcode in the phone for the vehicle, but that is generally explained in the vehicle's manual.