To work your glutes (butt) and hamstrings (back of the thighs) start by sitting on the roller with the soft, meaty part of your buttock directly on top of the roller. Begin slowly rolling back and forth and slightly side to side to release any tight sports in the muscle.
Slowly roll down your leg toward your knee and work the hamstrings in the same way. (picture above). Change your position from side to side to work the entire muscle. Slowly roll from the buttock down to the knee pausing on any tight or sore spots.
Increase or decrease pressure by using one or both legs at a time. Roll with your feet turned in and out to cover the entire muscle group.