On a Windows machine:

1.    Make sure the content you want to take a picture of (capture) is fully visible.
2.    Press and hold the "alt" key (just left of the space bar on the keyboard)
3.    Press the "Print Screen" button (in the right cluster of keys at the top of the keyboard).
4.    Release both keys.  The image is now on your clipboard.
5.    Open a Word document, and use File > Paste (or Ctrl+v).
6.    Add any text you desire to the page and save the document.

On a Mac:

1.    Make sure the window you want to capture is fully visible.
2.    Press and hold the "shift", "control" AND "apple" keys.
3.    Press the number 4 and release all keys
4.    Your cursor changes to a crosshair.
5.    Click and hold the mouse button to select the area to copy.
6.    Release the mouse button.
7.    Open a Word document, and use File > Paste (or "Apple" key + v) to paste the image into the document.
8.    Add any text you desire to the page and save the document.