how do I re insert the rubber gasket in driver door window that cushions the top on 2005 Nissan Pathfinder

The rubber gasket from the top of the drivers door window has come out. It's approx. 3 ft., has one rounded side and one flat side. I would like to reinsert it to cushion the window when it closes.

Asked by for the 2005 Nissan Pathfinder