How to become an actress?

I'm 12 years old and I'd like to be an actor. I live in a small town, and now I'm moving to Washington D.C. As long as I can remember I dreamed of walking the red carpet and maybe even getting nominated for an Oscar. I know it's a big dream and it will be hard, but I can't imagine myself sitting in an office desk my whole life. Plus if I do fail I have a back-up plan. I just need to know how I can get started. Thanks:D