Carreer in acting, and possibly singing?

My name is Kimberly. I'm 14 turning 15. Acting and singing have always been my lifelong dreams and I really want to make them into my carreer. However, I know that you need an agent (right?) and I'm not sure how to get started. I'd like to try and start on TV as young as possible, but I have no idea what steps I need to take. Can someone give me as much information as possible?