Check your toolkit and find the wheel brace and plastic nut spinner, you'll also need the Philips or Pozidrive screwdriver.
Open the hatch and look near the light cluster containing the bulb you want to change; you will see 2x screws on the 'outside' of the car and, after removing the rear speaker covers (slide them into the luggage area, away from the side windows - they can be a little stiff to remove), you'll see an oval rubber bung or cover.
Remove this rubber bung and you'll be able to loosen the nut inside using the wheel brace, then, after pressing the nut spinner firmly onto the nut, you'll be able remove the nut fully with it safely retained in the nut spinner. Once the nut is removed you can unscrew the 2x screws and remove the light cluster from the car carefully; you'll need to release the wiring loom by squeezing in the clips.
Place the removed light cluster on a suitable surface (I usually use the floor of the luggage area) and remove the 3x screws retaining the bulb holder, these are prone to rusting (particularly the lower one) and can seize inside the threaded section causing it to rip out of the unit.
Once the bulb holder is removed you can replace the bulbs as required then, as all the manuals say, refitting is the reverse of removal.
