If you go to YouTube and look up 'training dog to hold object' you will find a ton of videos showing you how to backchain like 3GSD described. I found those helpful. It does take a long time, with itty bitty baby steps, so be patient! Also, make sure you start with an object that is only used for that training at first. No tug ropes or toys that are used for anything else. After the dog has mastered the one object, then you can try other objects.