How do you start an acting career at the age of 16 for a Disney channel show?

I would start by creating a portfolio including all of the plays and musicals you've been in. If I were you, I would be in at least 5. Then get an agent that's close to were you live. If you're good then they'll sign you up for auditions. You'll probably start off with small rolls in T.V shows or commercials, but then if you show progress, you'll get in the real show business. Note; don't do this if you just want to be famous. You need to love acting if you really want to be an actor!!!!!