You grip his right leg with your right hand from under his leg, you grip his left leg with your left hand.
You are folding his waist, once you become opposite his legs, you had better do his waist does not alive.
You down with opening your armpit, pull out his knee inner direction and extend his knee. Then you should ride his legs on your left legs.
You control his legs with your left hand, your right hand be along his body, you hold him by "yokoshiho-gatame".