WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. 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