Windows 7 has a very cool tool included with it, called the Snipping Tool. This tool can be used to capture/save part of the screen or the entire screen as a JPG, or PNG file. The file can then be emailed, posted to the web, or used inside of Bb.
The Snipping Tool can be found using the Start menu by default on a new system it will appear near the top of that menu. If it is not located there, then click All Programs, near the bottom of the menu, look for the Accessories folder and click on it, then locate the Snipping Tool shortcut within.