I need help finding an agent!

Hi there. As you probably guessed it, yes, I am a teenager. However, I'm no "I wanna get rich and famous and be on telly!" kinda girls though. I am deeply interested in acting professionally, and I would like to take another step towards that career, by getting an agent. I know that there are alot of these sorts of threads, so sorry in advance. But I'm having a little difficulty knowing some good agencies and so on. I'm mostly interested in theatre work, specifically musicals, however, anything would float my boat. So anyone have any advice of which agencies I should send my resume into? I live in Melbourne, I'm fifteen, and I currently only have community and school theatre to my name. I would appreciate any help. Cheerio :)