you dont keep whistling to your dog you just keep saying its name again and again and if the dog barks stroke it keep saying your puppies name and eventually a note will come up saying
he/she seems very interested in you now youve called his/her name reapetedly, then your dog will have learned its name
hope this helps
i kept saying my dogs name repeatedly but nothing happened. i just got the impression that it was a continuous loop (and gave up).