Don't expect too much from a pup at his age. You train by making it fun for him and keep the sessions short. Put a short lead on him and when you you throw the object for him walk away from him and when he sees you going away he will run past you inviting you to play. As he goes past grab the lead and gently pull him to you. Let him hold the object a bit and then take it from him by rolling the lip onto his teeth exerting just enough pressure to get him to drop it. Then praise him and do this only a couple times before you play again. Remember he is like a baby yet.