How old is she & is she spayed? My girl became a serial humper after she was spayed, though mostly blankets or our younger dog.
Usually the 'leave it' command works to discourage her, but from your post it sounds that she doesn't have any basic commands yet, so that would be the place to start. Have a look for training classes in your area. You'll be best with positive reinforcement training - clicker training is usually very good.
Have you had her from a pup or is she a rescue?
