This "weatherstrip" is the long metal and fabric "fuzzy" piece that attaches to the top inside edge of the door panel, and protects the window from the door panel. Sold individually, see Related Items below for the passenger side.
Door Panel Weatherstrips are installed using special staples from the factory. An automotive upholstery specialist should have access to these staples (and the upholstery stapler as well) for proper installation. A strong silicone adhesive can be used instead as long as the weatherstrip is secured in place while the adhesive cures.