twist the plug, the one with the wires going into the lens lightly, its should then part, with the lens in one part and the wires,bulb and holder in the other, then its just a case of puling the bulb out, may be hot if you've just unlo9cked the car or had the boot open tho, and inserting the new bulbs in.
My tip would be if you get that far is put the bulb in the holder then either open the boot or lock then unlock the car to light the bulb up, if it doesn't light up, take the bulb out and turn 180 degree's.