arm bar from guard brazilian jiu-jitsu

Get your opponent in a closed guard position. In this picture, the person in the white gi has the person in the red gi in his closed guard.
Secure your opponent's right sleeve with your left hand. Cross grab his right elbow with your right hand. As you secure the arm, lift your hips off the floor to create more pulling force.
Pull his arm over and crunch his legs and chest in.
Open both legs at the same time and throw them up in a reverse crunch manner.
Click for closer view

Immediately close your legs and lock your opponent's shoulder up to keep him from escaping.
Squeeze both your knees to the left and block your opponent’s face with his hand so he can’t defend.
Place your left leg over your opponent’s face and extend your hips up while controlling the arm for the arm bar