As they say "You Tube is your friend" There is a guy on there, I think his name is Freddy??? He has a good step by step method, Freddy King, check him out.
My lab, Jessie is 14 weeks old, we have been in a 6 week "manners" class, getting basic obedience, socialization, etc. There are about 5-6 dogs in it, the trainer goes over lessons, we do them through the week, review and learn more. We have been doing fun retrieves in the back yard, I started shooting a cap gun while we are doing these fun retrieves, now I'm using .22 crimp blanks and she's doing great.
Bird wing on a string is next with some longer marks, REALLY stressing "HERE". will use a 30ft check cord.
Takes allot of time but your pup will worship the ground you walk on!!!
"I ain't here for a long time, I'm here for a good time"
King George Strait