<FFBDevice name="Logitech G920 Driving Force Racing Wheel USB" scaleForce="1.0" scaleFriction="1.0" baseFriction="0.0" maxFriction="100.0" scaleEffects="1.0" delay="0.0"/>
Once these files are edited you should then be able to launch the game and use the controller. You will need to go into the settings and configure each button on the controller to be used with the game. This can be done by just mapping each button to an appropriate action on the controller.
More information is available on the codemasters forum if you are having some issues: