How do I get an acting job?

I haven't ever acted in my life but my friends say that I would be really good at it because I guess I act without really realizing it. my best friend has been making me watch the Chronicles of Narnia movies and I realized it would be amazing to be apart of something like that. It's just I'm nervous and scared about what my mom will say. I'm 15 a sophomore in highschool. please anyone help me.