I have a ford focus 2002 and i'm instaling a new radio?

The radio has 3 wires (black, red, yellow and blue (blue is for the remote. I know that blacl is ground, red is power and yellow is memory. However, the car has 5 different wires. Fat orange and black, fat green and black, thin red and black, thin black and yellow, thin yellow and light green. Can anyone tell me which wire should go where?

I think you need to get a comverter

Buy a wire harness adapter for your vehicle. Any store that sells car audio will stock it.