How do I properly secure my child in the booster seat?

Place the booster seat firmly against the back of a forward-facing vehicle seat equipped with a lap/shoulder belt. Have your child sit with their back flat against the back of the booster seat. Position the shoulder belt through the shoulder belt guide (not over it), fasten the buckle, and pull up to tighten. The bottom of the headrest should be even with the top of your child's shoulders, and the lap belt must pass under the armrests and be positioned low on the hips. Make sure vehicle belts lie flat and are not twisted.