'globes' Not a term I'm familiar with? If you mean the bulbs then you just open the inspection panel under the wheel arch, take off the rear light cover, turn the rear of the light holder 1/4 turn unlip bulb and then fit the new bulb. Ensure the lights are OFF due to high voltage
I would however want to know what caused this problem and is it indeed the bulb. Xenon do not usually 'burn out' as they are gas filled and should last the life aof the car in most cases. Both out at once?? then I'd belooking at fuses and switches first, then ballasts and finally bulbs.