What should I do to properly secure my child in the Graco car seat?

Place your child in the car seat with their back flat against the back. Place the harness straps over the child's shoulders and insert the buckle tongues into the buckle, ensuring straps are not twisted. Pull the adjustment strap to securely tighten the harness, then fasten the harness clip at the middle of the child's chest level with the armpits. Make sure straps are flat and tight without any slack. (Pages 26-27)