I would suggest not starting with shaders. Start with the basics of game design. The manual is a great reference to have, but you should probably start with a tutorial, like the ones at http://www.3dgamestudio.com/

Good luck. My personal advice would be to stick with it. You will run into barriers, and sometimes it will seem impossible, but there are always ways to accomplish what you're trying to do, even if it doesn't work the first time ... or the second time ... or the twelfth time