
Firstly, read the first post on the Breeding forum of this site.
Both dog and bitch will have to be KC registered, with no endorsements on their pedigrees, and have been hip-scored (with a result of less than the breed average) and successfully passed all other breed-relevant tests for hereditary conditions (a general health-check by your vet is
NOT sufficient!).
Then you'll need to know that both dog and bitch meet the breed standard, and that their bloodlines are suitably matched. For advice on that you'll really need to contact other DDB breeders - are you a member of the breed club?