HOW: Using some sort of elevates surface like a box or bench, place the side you want to target on the box. Place the inside part of your ankle on this surface, use something soft for padding if you like. Lift your hips in the arm by driving the inside part of your ankle downward into the box and hold this position.
FEEL: You should feel all the muscles on the inside part of your thigh working, in particular, your groin region. You will also feel your core and shoulder muscles working. If you feel the inside part of your knee hurting with this exercise, put your knee on the elevated surface instead of your ankle.
COMPENSATION: Keep your hips stacked on top of each other, do not rotate them forward or back. Put your elbow directly below your shoulder.