Screen shots make your posts much more interesting and easy to understand. Here's how to do it.
1. There are many sites which host free images; I use
http://www.imageshack.us 2. With standard Windows you can capture the screen to the clipboard by hitting the Print Screen button (Control+Print Screen, or Shift+Print Screen do variations - one is entire screen, one is current window or something like that.) Once captured to the clipboard, you can paste it into an image editor such as the standard Paint utility (on the Accessories menu) and then save it as a JPG.
3. From the imageshack (or equivalent) website, there will be an upload mechanism; you browse to specify the JPG file, click upload; then it will display some links which you can cut and paste into the forum post to attach the image to the forum. I prefer the "thumbnail for forums" version.
4. The above can be further simplified by using a tool that allows you to capture a selected rectangle of the screen (rather than the whole thing or even an entire window). I happily use
Gadwin PrintScreen - it's free and gives you the option to capture by dragging the mouse to form a rectangle; it then launches your image editor and pastes the image, so all you need to do is close it, and then the image will be saved as
My Documents\PrintScreen Files\ScreenShot.jpg, greatly streamlining the procedure.