How do I properly position the shoulder belt in booster mode?

The shoulder belt must cross midway between the child's shoulder and neck and must be routed through the shoulder belt guide. The shoulder belt must not cross the child's neck or fall off the child's shoulder. If you cannot adjust the shoulder belt to properly lay midway between the shoulder and neck and at or above the shoulder, try another seating location or do not use the booster seat. (Page 11)