@ekim The majority of the time, this naturally happens through the connections you make via dog shows, your mentor or dog sport competitions (AKC retriever trials, field trials, agility, Hunt tests, competitive obedience and etc). The people competing in these events are usually dog breeders themselves.
If your dog is fully OFA tested, is of breeding quality and is titled, then people will approach you about breeding to your dog. They’ll see him competing in an AKC sport/working trial or conformation show and if they like him, then they’ll ask about it.
Though to be honest, Golden Retrievers are a very competitive breed. The overall amount of high quality, highly accomplished studs in the breed is high. As a result, just being AKC registered isn’t going to cut it since someone with a female Golden already has plenty of Grand Champion show dogs, highly accomplished working dogs and etc to choose from. All of which will be fully OFA tested in accordance with the GCRA code of ethics.
If you want a mentor to help you in getting started with all of this, then Robin Bowen of Prism Goldens is a great breeder who’s very friendly and welcoming towards newcomers. She’s often open to taking new breeders under her wing and helping them with starting out on the right foot.
Since your dog was previously a stud dog from another breeder, do you have breeding rights and pedigree information for him? The majority of the time, retired breeding dogs are sold to pet only homes on terms that don’t allow for breeding. So I wouldn’t breed unless you have permission from the original breeder.
The pedigree information part is extremely important because Golden Retrievers suffer from high rates of cancer. As a result, it’s extremely important to research the pedigrees of any dogs you plan on breeding to ensure that the resulting puppies have a good chance of being healthy, long lived dogs who won’t die of cancer at age 2.
Golden Retrievers have a great, free online pedigree database called K9Data. So if you have your dog’s pedigree or registered name, then you can punch that into K9Data to find out how long his ancestors lived for, what they died of if cause of death is known and so much more.