After stripping off the meat from the bones you want to make bone broth from you just fill a pot or crock pot with water and then place the bone or bones in the crock pot or pot filled with water.
Add some apple cider vinegar to the water and then let the mixture sit for at least an hour before cooking it.
After the bones and apple cider vinegar solution has sat for at least an hour then you can add vegetables to the mixture and then turn the crock pot on or bring the pan up to a boil.
Then skim the scum from the top and discard the scum.