Cadillac CTS Owner's Manual page 62

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.
62
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.