How do I place an insert into the frame?

First slide the insert down, just behind the safety tabs. Make sure that the bottom of the insert does not get caught by the bottom of the viewing area but instead slides all the way to the ground. Then, carefully slide the insert back up, gently pushing the top of the insert behind the top of the viewing area. Finally, slide the insert back down, resting the bottom of the insert just behind the bottom of the viewing area of the frame.