Buggy, all you do is have the window you want to screen shot open, and press the "PRT SCR" button on your keyboard. It takes a shot of that window.
You need paint or some other picture editing program for this next step. Open that program, and click paste (either right click, or from their options), and it pastes that screen into the program. Edit it, save it, then upload it onto a website such as Photobucket or Imageshack, then give the mod or administrator the link to the screen shot.