Step 1) Approach car.
Step 2) Stand behind the boot (or trunk if you're American.
Step 3) Push the boot release and lift the boot open. (REMEMBER TO UNLOCK THE CAR)
Step 4) Look inside boot.
Step...
Just replaced my backup lights a few days ago on my 1999 Navigator.
On the inside of the tailgate. You have to take the screws out of the pull strap that is located on the inside of your tailgate....