Although the title of Duncans thread is ' Manual exposure mode, juggling three balls ', in order to understand what your camera is doing in Modes other than manual, you really need to read this ....
http://www.worldphotographyforum.com...read.php?t=125
Even when using Program Mode, the aperture and shutter speed, that the program has selected will appear in the viewfinder display. If you have a basic understanding of how these numbers have been arrived at, then the displayed values will have some meaning as to their affect on the picture you are about to take.
Once you have an understanding of the link of these three things every other aspect of photography will appear easy. For that reason it is worth spending time on this.
PLEASE post any questions you may now have.
Don