To remove the headlight assembly, first use the 5mm nut driver to turn the locking nut 1/4* of a turn in the indicated direction. On the passenger side the nut is clearly visible; turn it clockwise.
On the driver side you will need to reach between the battery and the car body, using a nut driver with a long handle, to turn the nut counterclockwise.
* Try not to turn the locking nut more than 1/4 turn. Doing so may rotate it back into a locking position.