How can I get my parents to understand?

There might be another solution. If you can find a breeder willing to mentor you, you might be able to get started in junior showmanship showing their dogs. I used to breed many years ago and a teenage daughter of a friend was interested in showing, so I used to let her show some of my younger dogs in junior showmanship. It provided experience for the dogs as well as her and she used to help me out around the kennel. It is very tough to get started in showing without a mentor, so if you can find a breeder willing to work with you, you will be well ahead of trying to go it on your own. Go to some shows, and some breed club activities meet some breeders, offer to help out in exchange for some help showing. You never know what might happen. And at least you will learn what "show quality" is before getting a dog.