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

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 booster seat back. Position the shoulder belt through the shoulder belt guide (not over the armrests), fasten the buckle, and pull up to tighten. The lap portion must pass under the armrests and be positioned low on the hips.