Jack needs to screwed to just about maximum down position. Then, it lays across the back side of the tire area with the bottomo of the jack to the far right and lifting lug dropping down into the well--there should be a piece of carpet glued there to prevent noise as the lifting lug contacts it. The cranking handle is then on the top side. The top of the jack nestles into a black plastic holder toward the left side of the well and there should be a gold metal clip that fits around the jack at about its middle.
'07 GL320CDI, '06 SLK350