Feed it two or three times a day, depending on your dog's size and diet. Puppies need to be fed more.
(Puppy) Feed your dog until it is full. Be careful though, as puppies meant to be in the wild or hunting will eat more then they need and turn it into fat.
(Adult) Feed your dog 2 cups of food. this varies from dog to dog. Those dogs living in cities with little outside play need less then dogs in wide open spaces. The size of your dog matters too, if it is a 15 pound dog it needs less food then a 115 pound dog.