Is this module installed locally? If so, you are going to need

use lib '/site_path/directory_above_you_module's_directory';

...near the top of your script. This will give @INC an additional path to look for (and hopefully find) your module.

$PM = "Perl Monk's";
$MCF = "Most Clueless Friar";
$nysus = $PM . $MCF;