A guide set my Canon 5D Mark ll to require 2 clicks before the shutter releases so it wouldn't shake while shutter open. How do I get it back to 1 click?
To me this sounds like the Mirror Lockup custom function setting. When using a tripod this is useful as it first locks up the mirror to avoid the shake from that as the picture is taken, allowing the camera to be as still as physically possible when the second click opens the shutter (assuming you use a cable release).
This can be turned off in the menu under Custom Functions (the 10th tab along in the menu, or 3nd from the right) with this particular option in the third menu down called Autofocus/Drive, and on the 5d mkII it is labelled C.Fn III -6 as you scroll along in this custom functions menu. It will mention Mirror Lockup by the numbering, and you will want to change this to Disable.
If you would like some brief explanations of what all the custom functions do on your camera have a look at the Canon site here