breeding for a toy yorkshire terrier.?

There is no such thing as a "toy" yorkie. He is simply undersized.
http://www.ytca.org/faq.html#A

Therefore he should not be bred. No good breeder would use a dog that wasn't standard.

If you need to ask this question here it is a sign that you don't know anywhere near enough to be breeding.

Please go do some serious research on responsible breeding.

Start here:
http://learntobreed.com/
http://woodhavenlabs.com/breeding.html
http://dogplay.com/breeding/index.html
http://www.gomestic.com/Pets/So-You-Want-to-be-a-Dog-Breeder.74279
References :

First save a few grand! for all your pups & vetting bills, Take him to Loads of high end dog shows to get him shown as a 'top of his breed', Get a breading Mentor, Get all the expensive DNA & heath tests, KC registered? Read up on why your dog is of such a high standard that breeding will be doing that breed a favour to carry on the blood lines, Then find a bitch that has all the same, Read up on everything possible to do with breeding and keeping pup's from new born + any problems that might arise from any aspect mentioned above

Now, you are ready
References :

If you don't even know how to find a dog to mate with, then you are going to be in trouble with the rest of the process. And again, there is no such thing as a toy yorkie, the dog is under the breed standard and that alone should be enough to deter you from breeding this dog. Get him neutered.
References :

Did you know? When you breed a dog it effects 13 homeless dogs in the world? And when you don't breed it saves the life of 9 homeless dogs out there. So stop and think about it… Would you kill 13 dogs in the world or save a life of 9 dogs?
References :
Proud Owner of a Beautiful, Healthy Shih Tzu!

All Yorkshire Terriers belong to the Toy group and all are supposed to be under 7lbs - there is no such thing as a "Toy" Yorkshire Terrier.
If you are planning on using him for stud, his breeder should be the person to advise you - assuming they are knowledgeable, experienced and reputable. If they are not, chances are your dog isn't of a good enough standard to be used at stud. Why would a reputable breeder want to use your dog on their quality female when they could go to a proven stud producing top class puppies?
There is far more to breeding than just finding a dog of the opposite sex - you wouldn't want your dog's puppies ending up in unsuitable homes or being dumped in rescue would you? Neither would you like his temperament to change and him to be marking your furniture and curtains - both things are possible once he is used at stud.
Since Yorkies are already so small, it is common practise to use a dog who is smaller than the b1tch - that way it lessens the risk of the b1tch producing huge puppies and leading to whelping problems.
http://www.thekennelclub.org.uk/item/199
OK, so you don't want to be a breeder - but you are 50% responsible for any puppies your dog produces - for the whole of their lives and letting him mate once is pointless - it's enough to change his temperament and having him seeking out every b1tch within 5 miles who comes into season. Leave it to the people who really know what they are doing.
References :

put a ad in the paper advertising him as a stud.read up on breeding.thats how i found female poms to breed with my male pom.
References :
byber