Here is another quick video. This one is a few Pilates exercises that you can do anywhere to help strengthen the back. Only take the back bends as high/far as you feel comfortable. Keep your core engaged to support the lower back. Lengthen the neck and keep the head inline with the rest of the spine, and the shoulders relaxed down the back. Also try to think “equal length, equal strength” as you practice the moves. As you lift into each pose think of moving your heart forward, and your feet back to help lengthen the spine and the muscles of the back.
Most importantly: KEEP BREATHING! Do not hold your breath in backbend, back extensions as you want to release any tension being held there, and breath will allow you to do so.