Polly,
You need to paste it at a command prompt. Which version of Windows are you using?
Windows 7: from the desktop, click on the 'Start' menu, then type 'cmd' (and enter) in the search box at the bottom of the Start menu.
Windows 8: from the tiled start screen, just start typing 'cmd', and 'Command prompt' should pop up as the first search result.
Hope that helps,
Ben