The acrylic shell has to be held at the same time as you are trying to align and screw the mounting fixture to the ceiling. It should be designed to install and screw the mounting piece into the ceiling, and then add/ hang the acrylic piece to the mounting piece in the ceiling. Also there are 2 screws that have to be aligned and screwed into the mounting bracket. We had a problem with the screws in the ceiling bracket not being long enough to go into the 2 metal circles (look at pic close). It took a lot of adjusting. The fixture looks great once installed, but took at least 4 hours.

Beautiful fixture