You must start off with a good solid recall and treat the dog every time he comes back to you, with a small ammount of cheese, chicken or anything he likes. Once you have a good recall, then and only then move onto throwing a ball, dummy, dont throw it a long distance 5-6 foot is plenty to begin with, when the dog picks the object use what ever verbal cue (command) so the dog returns to you (he should do this as he is used to returning to you for a treat) when he comes to you take the ball, dummy and give him a treat (just like the recall). Dont do too much as to sicken the dog i advise only