
You need to continue with you're education in HS and college. I would recommend a Business degree for college.
You can start learning about dog shows by actually the shows as often as possible. Decide which breed of dogs you are interested in then start talking to the breeders and handlers of those dogs. It takes many years to get to the point of a handler at Westminster.
They have Junior Showmanship at dog shows. Try to locate a local training/handling class where you live and start there.
What you see on TV has taken those handlers and breeders years to acquire the experience of handling a dog correctly.
Many aspects one needs to learn about correctly showing a dog. This you can learn from training classes with local breed clubs.
Hope this helps.