A "screenshot" is a snapshot of what's on your computer screen, stored as an image file.
In order to create a screenshot, please follow these steps:
Open the windows you wish to capture, and leave them up and visible on the screen.
On the right-hand side of your keyboard, you should see three groups of keys. The lower set of keys usually is a group of arrow keys. Above that is usually a set of some six keys that are labeled "Insert," "Home," "Page Up," etc. Above that should be three keys that have rather odd labels - like Pause/Break and Scroll Lock. One of these keys should be labelled "Print Screen/SysRq", or "PrtScrn/SysRq". Pressing Alt+PrintScreen (Alt+PrtScrn) places a snapshot image of the frontmost window on the clipboard. Pressing PrintScreen by itself places a snapshot image of the entire desktop on the clipboard.
Although when the PrintScrn/SysRq buton is pressed, it appears as though your computer has done nothing, your computer actually took a snapshot image of the screen, and stored that picture on its clipboard.
Open MS-Paint. (From Start/Run, issue the command "mspaint".) Create a new empty image, and use Edit > Paste to bring in the screenshot you just took. (If the screenshot is smaller than the default Paint canvas, you will end up with empty white areas. In this case, start over: create a new empty image, change its dimensions to 1x1 (using the "attributes" option), and paste again. The canvas will grow for the paste, but it will not shrink.)
Use MS-Paint to Save As, using PNG as the file format, for the most efficient storage.
The above instructions should work on all versions of Windows.