The parcel shelf, or package shelf as it is sometimes called, is the carpeted part of the interior of your car located immediately under the rear window and behind the upright backrest portion of the rear seat of the car. In many cars, the package shelf is one of three locations used by car manufacturers to mount speakers, and it's also the most easily accessible speaker mounting location when installing replacement speakers in a car.
Open the boot of your car and position your head near the back of the rear seat. Look up and you will see the parcel shelf speakers above your head.
Pull the electrical connectors off of the electrical tabs on both of the parcel shelf speakers with your fingers. Use a socket wrench to remove the four nuts that secure each of the speakers to the underside of the package shelf.
Position the replacement speakers where the original speakers were located, threading the mounting bolts through the replacement speaker mounting holes at all four corners. Install the nuts onto the mounting bolts then tighten them down with the socket wrench. Install the electrical connector onto the replacement speakers by pressing the clips onto the speakers' electrical connectors. One connector is smaller than the other for both the speakers and the wiring to simplify installation.
Replace stock speakers with speakers of greater quality for the best possible sound from your radio.