There are a couple ways to take a screen shot.
I think the easiest way is to download FastStone Capture ... you can test drive it for free, and paying the $19.95 license probably won't break the bank.
Once you've installed FastStone, you'll have a little toolbar handy, you can position it anywhere on your desktop.
If you want to select just a particular area of your screen, you click the third tool over, the rectangular marqee. First you'll see red crosshairs, click to position the crosshairs at your starting point.
After you set the starting point, just drag over the section of your screen you want to capture. As soon as you release the mouse button, the FastStone editor will open, with the captured section of the screen diplayed.
You can then click on the T for access to the drawing tools, to add circles, boxes, or arrows.
You may find it interesting that FastStone balked at taking this screen shot of itself, so I used Kristal Kraft's favorite, SnagIt -- Snagit is $39.95, so it still won't break the bank, and SnagIt also includes some really cool call-out shapes, like this:
But I'll leave posts about Snagit for Kristal. :-) I use FastStone more often, because for me it is so simple and convenient.
Did you know you can also take a screen shot in Windows without installing any special software?
Hit your PRT SCR button, usually near the upper right side of your keyboard.
Hitting that button copies the entire screen contents into your Windows clipboard.
Open an image editing program, such as Photoshop Elements Hit File -> New . Hit Edit -> Paste.
There, the screen contents are now displayed in that new file. You can crop, sharpen or resize as needed.
If you don't have an image editing program, you can just open MS Paint, or even MS Word, and Hit File -> New, then Edit -> Paste. You just won't have as many editing options.