Cadillac 2004 Seville Owner's Manual page 44

3. Buckle the belt. Make sure the release button is
positioned so you would be able to unbuckle the
safety belt quickly if you ever had to.
1-38
4. To tighten the belt, push down on the child restraint,
pull the shoulder portion of the belt to tighten the lap
portion of the belt and feed the shoulder belt back
into the retractor. If you are using a forward-facing
child restraint, you may find it helpful to use your
knee to push down on the child restraint as you
tighten the belt.