Taking and saving a screenshot in Windows XP

1. Press the "Prnt Scrn" button.
2. Open Microsoft Paint. To do this, click Start > All Programs > Accessories > Paint. Click inside the white part of the screen.
3. Go to the Edit menu and click Paste or you can press and hold "Ctrl" and tap V.
4. Click File > Save As. In the box that pops up, change the "Save As Type" to PNG or JPG. Type in a filename for your image. Choose a place to save, like the Desktop, and click save.
5. You have now successfully taken a screenshot! If you want to send your image to somebody, simply attach the .png file that you just saved to an email and send it along. Alternatively, you can upload it onto the internet by visiting a site like photobucket.com or flickr.com and uploading it.

Taking and saving a screenshot in Windows Vista/7

1. In Windows Vista (except in Home Basic), there is a tool called the Snipping Tool.
* To open it, click on the start menu, type snip, then hit enter (the latest version of Windows Vista updates the search results as you type each letter).
2. Click on Snipping Tool.
3. The Snipping Tool opens, and a white mask is applied on the screen. In the drop-down menu for the 'New' button, choose from a free-form snip, rectangular snip, window snip, or full-screen snip.
4. In free-form snip mode, draw around the area you want to be captured. Drag a rectangle in rectangular snip mode. For window snip mode, select the window you want to capture. In full-screen mode, just selecting it from the drop-down menu makes the capture.
5. The snipped image is then opened within the Snipping Tool, but is also copied to the Windows clipboard for use in other applications.

Taking and saving a screenshot in Mac OS X

1. Hold down the APPLE [Command] and SHIFT keys
2. Press 3 for a screen shot of the entire screen
3. Press 4 to get a "Crosshairs" so you can select just a section of the screen you want a screenshot for.
4. Press the space bar after you press 4 if you want it to automatically size the screenshot so that it perfectly matches the window it's over. After you press the space bar, a camera icon should come up.
5. Know that the resulting file will be placed on your desktop, named Picture X.pdf for versions of 10.3 or earlier and Picture X.png for 10.4 and later (could also end in .jpg).