Hotcoder,
Look at my response to JHA in this thread
http://darkbasic.thegamecreators.com/?m=forum_view&t=32618&b=4
While this is a top-down 2D rpg layout, the same exact prinicples are used in 2d platformers that are tile-based. Of course, you would want to add a background image (or multiple images for parallax scrolling).
The code in the thread is a good place to start. With platformers you probably won't need 5 layers of tiles though. After you get the idea of how the code works, you should than look at the "altered beast" demo code. It will help you to understand parallax scrolling.
I'll try to answer as many questions as I can.