Sit in sukhasana or dndasana, on the floor with your pelvis in a gentle posterior tilt and your knees bent, separated, and resting in an easy crossed position (right leg on top).
Hold your right calf with both hands, and rotate your tibia (shinbone) away from you (laterally). Keeping that rotation, close your knee by drawing your right heel toward your navel.
Extend through your right foot in plantar flexion (toes pressing down). Place your right foot into the crease of your left hip, and reach through your right femur (thighbone) so that your right knee moves down toward the floor.
Repeat the same process for left leg, touching its heel to your naval, but put the leg above the other one.
Take deep breathes and hold the position as much as you feel comfortable, then come back to starting position and relax.
Practice Keynotes
Keep your spine and neck straight.
Focus on your breathings.
Cautions and Limitations
Don't pull the legs to fold them harshly.
Avoid facial contortions and excessive shaking of the body.
Proceed carefully and only under expert guidance.
At the slightest sign of discomfort, reduce the duration of practice and, if necessary, discontinue the practice for the day.
Practice should never be rushed.
Contraindications
Don't do it if you have any leg injury or knee pain.