You get a fee for putting your dog out to stud.  You also have to provide papers to show the dogs lineage or simply put, who the parents were and if they were pure Doberman.  If you have a pure Doberman, what is recommended is that you only mate your dog with female pure bred Dobermans.  The reason for this is that if you mate your dog with other breeds, then you get a mixed breed dog.  These pups are not always desired, and often end up not being adopted out.  Many pet owners want to make money with their dog, and if you breed with a dog that is not full blooded (whatever the type is) then they bring less money.   You can advertise on Craigslist.com in your area, under the pet column, that your dog is ready for stud service……..you put the age, size, weight, height, who the parents were, if the dog is good with children, what kind of disposition he has, and if he needs a lot of exercise.   You can look at ads on line for general information about FEE amounts.  I have seen them start at $300 to $500 if your dog is a pure bred Doberman.   Often, people check with their Veterinarian because your vet can recommend you to people who are looking to mate their dog.   Veterinarians have a good idea of how much to charge, and which dogs would make suitable partners.