There's a few different ways that you can use apple cider vinegar for curing and getting rid of bad breath.
You can take a tablespoon of apple cider vinegar and swallow it before you eat a meal, or you can dilute the apple cider vinegar into a glass of water and drink it after each meal you eat.
You can also use the apple cider vinegar as a mouthwash and take a tablespoon or just put some apple cider vinegar in a small cup or medicine cup and put it in your mouth like you would regular mouth wash and rinse your mouth out with the apple cider vinegar and then spit it out.