this is the desktop; it's pretty simple. the figure should pretty much explain what everything is.
i'm going to assume that you at the very least know how to navigate your way around a computer, so i'm not going to get into great depth here. for example, you should know that you can't delete the recycle bin, even though we will do it later anyway. what you may not know is that many programs, scheduled tasks, and even websites rely on your system's clock. changing the date and time can mess things up, or even reactivate some expired trial-software. the main thing we're concerned about here is reverse-troubleshooting, learning why our average computer user is the real threat. think of somebody who is not very savvy with computers, and imagine yourself sitting in front of their machine.
start > all programs > accessories > entertainment > volume control
mute all sounds and close it. now how long do you think it would take before they ask you what is wrong? in most cases, it wouldn't take long at all. it is at this point you should make a note to yourself not to type any passwords or order anything with your credit card on this individual's computer, because it is more than likely swarming with trojan viruses.
it is going to get worse before it gets better.