Remove old line in holder. Measure proper amount of new line, cut with knife. Put line in the small hole in middle of holder. Wrap line in clockwise direction
This requires taking the head of the trimmer off. It's not to complicated, just start taking the bolts out for the head of the unit, and the problem should present it's own solution. It just takes restringing the head once it is off of the unit entirely. Then re attach the head once it's restrung.