To use this Purina Pro Plan dry cat food, simply measure out the appropriate amount according to your cat's age, weight, and activity level and place it in your cat's food bowl. Make sure to provide fresh water at all times. As for storage, keep the bag sealed in a cool, dry place to maintain its freshness. If you're transitioning your cat to this new food, do it gradually over 7 - 10 days by mixing increasing amounts of the new food with the old one. Monitor your cat's reaction and health during the transition. If your cat has any special dietary needs or health issues, it's always a good idea to consult your veterinarian.