I'm new to blackberry and very excited about getting to know it. I have the Curve 8530. One of my friends told me "Welcome to the Darkside" and "I'm going to get addicted". LOL
Check out the BlackBerry 101 How-To Lecture Series ! This will help you with the basics such as downloading apps, themes, wallpaper, ringtones. It's also a good idea to browse the forums and read as much as possible. Many questions you have are answered there already!