[hcelsa]

Basically it's a registry so that high risk (sometimes called "backyard" but I prefer high risk as it's a more descriptive term) "breeders" (and I use the term breeders very loosely in this case) can sell puppies "with papers". I sincerely doubt that you will find a RESPONSIBLE breeder out there that has dogs registered with this organization (and a responsible breeder wouldn't be sending puppies home at or before 6 weeks either).
My guess is that in this case, you're out of luck if you were hoping for AKC registration (if your dog is spayed/neutered and looks like a Rottweiler you can get an ILP number though which will give you the opportunity to participate in performance events).