How do I Turn on the viewfinder on the Olympus E-500 when taking a picture?

Question

I can view pictures taken but how do I use it as a monitor?

Answer 1

You can't. The display is only intended for reviewing pictures and accessing the menu. It's like that with all digital SLR cameras with the exception of the Olympus E330.
That's because the image from the lens is reflected by mirrors straight to the viewfinder - there's no room to put a sensor in that path. The E330 is a horrible engineering compromise and it suffers from several drawbacks of point & shoot cameras, such as sluggish performance.

Answer 2

RTFM the Olympus 330 is the only DSLR that permits this. The e-500 is a standard DSLR you have to use the viewfinder.