Lie on your back on a firm surface with your legs extended up the wall. You may need some help positioning yourself.
Using the weight of your leg, but in a controlled fashion, slowly lower the one leg, sliding the foot down the wall.
When you have achieved maximum flexion, hold it for 10 seconds, and slide the leg up again. Repeat 5 times.
You can alternate with the other leg. Repeat each 5 times.