Just follow these steps:

Step 1
Starting Position: Lie on your stomach over the top of the stability ball. Begin in an all-fours position with your torso on the ball and hands and feet on the floor. Lengthen your legs and stretch your heels to the back of the room. Your hands should be under your shoulders.
Take a few deep breaths. Notice how your abdominals want to rest on the ball when you inhale.
Exhale and pull your abdominals away from the ball. Try to keep them pulled away even when you inhale. This is your abdominal engagement

Step 2
Outward Phase: Gently exhale. With your abdominals engaged and your torso rigid, slowly walk your hands forward, lifting your legs off the floor. Your legs should be actively reaching toward the back of the room. Avoid allowing your legs to droop. It is important to keep your ribcage knitted together and the abdominals strong in order to maintain a rigid torso. Continue walking out until the fronts of your thighs or knees are resting on the top of the ball. The further you walk away from the ball, the greater the stability challenge. Go slowly and find the challenge that is just right for you. Keep your body rigid so that your legs and trunk form one continuous line. Your legs should be very active so that your entire body is straight as a board and aligned parallel to the floor.
Keep your shoulder blades pulling away from your shoulders and toward your hips. Your end position is where you can maintain stability with your hands directly under your shoulders, and elbows, torso and legs straight and strong. Hold this position briefly.

Step 3
Return Phase: Inhale and slowly walk yourself backwards to your starting position, trying to maintain your stability and balance, moving backward smoothly.

Source: Greatist