Xmonad/Config archive/Template xmonad.hs
Use a template file for your xmonad version from the Xmonad/Config_archive
% xmonad --version will tell you what release version you have. If you are running from darcs hopefully you know it already, since darcs will still show the version of the latest release.
You also may have a sample xmonad.hs that came with your installation somewhere like $docdir/xmonad/man/xmonad.hs or with the xmonad source. Often /usr/share/doc is $docdir.