Stretch exercises for the back

I have told to do some stretching exercises today.  It would be very helpful for my back.  I have had back problems for a while now and I was supposed to have exercised at least twice or 3 times daily.  I was even asked if I had exercised.  I told them about the stress that I have been under and that I hadn't done much exercise for my back.  I was told that my back condition would improve if I would do some stretches.  So that is exactly what I am going to do.