WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Rear Compartment Lamp
Courtesy of GENERAL MOTORS CORP.
Install the bulb to the rear compartment lamp socket.
Install the rear compartment lamp, pressing into place until full seated.