How do you add air to shocks on a Pontiac Bonneville?

You don't add air to the shocks on a Pontiac Bonneville (or any other car, for that matter). Car shocks (also called dampers) are hydraulic, not pneumatic (air-filled). They contain hydraulic fluid, not air. If your Bonneville's ride is rough or bouncy, the shocks likely need to be replaced, not refilled with air.