(Because I can't post my desktop...)
:o[
1. From the keyboard, "Print Screen" to get an image on the clipboard. (This might vary from machine to machine.)
2. Open up a graphic editor and "Paste" as a new file (Microsoft Paint is actually good at this!). Save it somewhere.
3. Open up some graphic editor that can resize and convert file formats (I used to use Corel Photo editor, today it's something call "Art Explosion (something)"), open the saved file and re-save (or "export") it as a JPG or GIF.
4. Get an account on Photobucket.com and upload the picture file.
5. Copy the URL and past in an FR posting.
Like I said, it's a lot of work! I've done it often enough, for various reasons, that I can zip right through it. But there is quite a bit of learning curve involved...
Truth be told, it's something I've figured out only a few weeks ago--I didn't even know I had something to do it.
IIRC, in Windows, you would do a Print screen at the desktop.
Then, go to an image hosting site (e.g. ImageShack.us). You should get an HTTP link to the image.
After that, you should be able to post it here--remember the <img> tag.