Lie on a flat surface such as a bench or the floor using a mat or a towel to cushion yourself.
Bend you knees until your feet are flat on the floor. Keeping your upper body on the floor throughout slowly and with a controlled movement raise your hips from the floor. Hold it at that position for a few seconds at the top of the arc and then lower it slowly maintaining control throughout. It is important that you do not allow your body to drop suddenly while lowering as you will not be using your muscles adequately if you do. You should do a full set of these.