How can i find an agent that will help me get on Billy Elliot on Broadway?

I am 13 and i have dance experience and i would love to be on Billy Elliot as a Ballet Girl! A Ballet Girl is one of those girls in Billy's dance class and they are in many parts of the musical! i would love to be in that musical! I already asked questions like this one and someone told me to get an agent and i dont know what type of agent! Do i need a theatrical agent or a different type of agent? plz help me!!!!! also can u tell me where to get an agent! I am young and i dont know how many agents acept young actresses and deal with broadway business! plz help mee!!!!!! this is my dream to be a Ballet Girl on Billy Elliot!!!