The inner ring is the bit with all the 13 pins sticking out.
The outer ring is the bit with the round extension sticking up.
Both parts when in their correct positions, looking straight at the pins, there is a small locating lug which should be at the bottom of the bit with pins in, and the round extension bit should have the extension at the 3 oclock position.
As you turn the plug to mate with the car, the lug stays at the 6 oclock mark, and the round extension now is at the 9 oclock position,,,,,,,then the plug and socket should mate and a turn of the outer with the extension to 12 oclock will lock the plug in place.