WARNING: This page is about a different car, the 2005 GMC Sierra and 2005 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Install the bulb.
Fig 1: Disconnecting Dome Lamp Electrical Connector
Courtesy of GENERAL MOTORS CORP.
Connect the electrical connector.
Fig 2: Removing Dome Lamp Assembly
Courtesy of GENERAL MOTORS CORP.
Install the dome lamp assembly into the headliner.