Answer:
You can search the show you want to appear on in Google or yahoo (just type in auditions for "THE NAME OF THE SHOW HERE" guest star), a bunch of websites with information about it will pop up. Keep picking ones. Take down all phone numbers and addresses, contact them, and wait. You'll get an appointment with casting directors and you'll have to act your heart out! For help, youtube has audition tapes of Demi Lovato and Miley Cyrus, channel them and one day your dream may come true...HAY you might even have your own show one day...that's how people like Bridgit Mendler started out! Websites like www.exploretalent.com are websites that actually set up appointments for you with Disney workers. Of course, you need parent permission and other paper work and struff but go for it! Im sure you'll land a gig someday...try nickelodeon and Disney XD id Disney dosent go too well...good luck!