WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
Fold the safety belt as indicated.
Fig 1: Folding Safety Belt
Courtesy of FORD MOTOR CO.
Pull the safety belt tongue over the fold in the safety belt.
Fig 2: Pulling Safety Belt Tongue Over Fold In Safety Belt