South Africa looks very organized. Here is the link for the Kennel Union of South Africa.
http://www.kusa.co.za/home.php
according to the info on that site, the shows in S. Africa are under FCI the same rules etc as in Europe. They are well respected.
Start there, find local dog clubs and local breeders who are willing to help you get started showing. You said you have been to shows, why didn't you talk to local breeders. My bet is that you would hve to convince them that your itentions are honourable which is the case in any country.
If you are not willing to show, then how would you know what a decent Yorkie looks like? No one will sell you a quality Yorkie for this type of breeding, no matter what country you are in. Your original post said you were looking for stud dogs to breed that were to standard. From your posts following it doesnt' sound you know what the standard is as you bought a chocolate Yorkie not realizing it is an incorrect colour. If you bought him for pet, have him neutered at the appropriate time but I have no idea why you would buy him if you want to breed if your best interest is for the YOrkie breed.