1. You're not using a namespace.
Two, the answer is two. It didn't have to be. It could have been one. Namespacing all of your code is good manners, and it's easy to do. Here's an easy way to namespace.
2. You're a magician, creating variables out of thin air.
If this looks foreign to you, I'd like to introduce you to my good friend Google. Google is good at helping people learn about things. OOP is way too big of a topic for my short, comically condescending, numbered list. If you need help finding Google try using your favorite search engine.
5. You're using the new keyword like a blind guy with a cross bow.
Edit Huge thanks to rogeliorv and Jared Wein for pointing out the error in point five. You guys rock.