Well, there are three main things that you're going to probably want in order to make it to broadway. Me---I'm Hollywood bound. So I know where you're coming from.

Build a resume. Do theatre, dancing, etc etc...Even if its small-time, local, independent, or the like, it dosn't really matter. Just try and make it so that when you start submitting yourself, you've experience under your belt.

Next step is actually getting a few shots done. These are just little tiny portraits of yourself. You really don't need much to find an agent, but once you do find an agent, its a MUST that you will have headshots of great quality to submit. Because these shots will be the epitome of who you are, so you must be presentable with that shot.

Agents are always a plus, of course. And in a round-about way, a must. They are the ones who help book you, and believe me--They want to book you that high-paying job.
To get into Broadway will be a hard road ahead of you, but just know that I'm right there alongside you. I'm off to try my best for LA in a year once I've developed my body, my soul, my resume, and my checkbook. =P