you need to open the trunk pull back the carpet, take of the black plastic backing w/ the tacks/pins and then get a socket/wrench to undo the bolts/screws from the inside of the trunk because you need to detach the entire light to get to the bulbs
e40 is correct! One important thing is to use a rag or thick pair of gloves because if the bulb fails and loses it's vacuum the bulb can be brittle and as soon as you grab it to pull it it may shatter in your hand I saw one customer that wanted to replace his own bulbs (for a failed state inspection) and instead of getting a fresh inspection sticker he got 14 stitches in his hand! So be careful as these can be dangerous!
In the rear trunk or hatch area, Your gonna have to remove the interior carpet liner around the back trunk area. Should either have plastic push plugs or just crimped with plastic trim with screws. Once you remove that about 4-6 screws to remove dust over, Then bulbs should be there.