It's quite simple. I'll assume that you're using some sort of Windows PC.

Go to Control Panel by opening the Start menu bottom-left.

Somewhere in there you should find an icon referring to your camera if it's built in. I have an external camera, so I had to install software first, but if yours is built-in, it should be there already.

Once you open that icon, you can adjust some basics re: audio and video.  You'll want an acceptable microphone level and settings that allow your picture to appear the way you want it.

That's it for set-up.

Most people would then use the camera with Microsoft's Instant Messenger (now called Windows Live Messenger). It's free and should be on your computer already in your Programs folder.

Once that's launched, go to Show Menu>Tools>Webcam settings and walk through the instructions there.

Once you're all set, make sure the person you want to see you is also set up.

You don't have to use Windows Live Messenger for this. Any application that allows webcam sharing will have similar settings.

If you have a Mac, the basic camera settings are in System Preferences, and again, you'll have extra settings once you're into whatever video sharing program you use. 

Most web cams will also have a small piece of software that will just let you take your own pictures even if you aren't sharing with others.