To make it in show business as a lighting designer, you'll need to at least get a degree in broadcast arts, fine arts, theatrical design, or something along those lines. You could even go on to get your doctorate, so then you could tend to any lights that fall ill during production. What? That's not how that works? Okay, never mind about the doctorate part.
If you want to break into the business, it always helps to pick up some experience along the way. Before even signing up for university classes, you could work the lights during plays at your high school or at other local events. Make sure to get up close and personal with that spotlight—you'll need to know everything about those if you plan to incorporate them into your lighting design for a Broadway show someday.