I am trying to locate the convertible top fill hole/port on a 2000 SLK230 can anyone lead me in the right direction

In the trunk as you staring into it, it is behind a plastic panel door on the passengers side (which will be on your right side if your facing into the trunk). There is a plugged hole on the side of that White tank and you will see the two lines molded into the tank for low and full.