Here's the service manual description and images of how to replace the bulb. For extra gits and shiggles, you'll see they refer to it as the rear fog lamp, and of course in North American versions of the car, we have no such thing. What the instructions are referring to is your backup light, mounted in the lower center of the rear of your vehicle. As @mtnghost
noted, you don't need to disassemble anything to swap out the bulb, and in @ameridan
's site and link he provided for bulbs, you'll be able to see what spec you need to get a brighter LED replacement for the OEM bulb.
Related aside, maybe I'm playing with fire, but I have never disconnected my negative battery cable to make bulb swaps. Seems like overkill to me, especially given that the negative cable has that somewhat fragile and bloody expensive piece of electronics attached to it. Then again, I'm neither a mechanic nor an electrician, so take my comment with a grain of salt.