With your dog facing you, stand still and give the command ‘Sit’. Have a treat or favourite toy in your hand and after a second, move it towards and slightly above his head and over towards his back, so he’s forced to look up at it. His bottom should automatically descend to the floor. Congratulate and reward him when he is sitting down.
Release him from sitting down by giving him another command to allow him to play, for example ‘OK’ or ‘Go on’.
Keep practising this exercise until your dog knows what to expect and reliably performs the action.
Making sure the command is clear, gradually adjust your hand movement so you do not always give the dog a treat but the arm movement becomes a hand signal.
Continue with the exercise, and restrict the treat-giving to random occasions when your dog has performed exceptionally well. Eventually the action will become habitual and the treat can be eliminated completely. Don’t forget that you should always reward your dog when he does something you ask him to do. A kind word, a pat or a brief play are all subsitiutes for food treats and just as welcome by most dogs. if you maintainthe hand signal it will be easier to control your dog from a distance and he will still be able to obey you when he can’t hear what you are saying.