I'm currently using Photoshop CS4 so things may be a little different but here are a few ideas. Go to Deviantart.com and download brushes. They have a ton of different brushes of various things. I would try Star brushes and see what you get. Download one (watch out for permissions. If they are used for personal fun stuff it's generally ok, but commercial stuff not so much.) Once you've downloaded the brush, select your brush too and look for a option to "load brush" You may have to search around to find. You'll then see it pop into your brushes palette. You can always look on you tube as well. I have used you tube a lot. Even if the versions of the program are different the principle is normally the same. It just takes some searching around.
Hope this helps,
Good luck
Sara