The Blackberry FAQ is a terrible thing to waste. Highly recommend you browse through the various FAQs listed and many of your questions will be answered. The FAQ can be found simply by looking at the menu bar at the top of each page.
To get you started, here is the direct link to the Tips and Tricks FAQ. Tips and Tricks - BlackBerryFAQ
Scroll down and you'll learn various navigation options to help you scroll thorugh the messages.