Thanks. By reworking one of the examples I was able to put together a code which opens the Firefox browser, loads the CPAN search page, fills in the query field with 'WWW::Mechanize' and then submits the form:

#!/usr/bin/perl

    use strict;
    use warnings;

    # the module we're looking for
    my $module_name = 'WWW::Mechanize';

    # create a new browser
    use WWW::Mechanize::Firefox;
    my $browser = WWW::Mechanize::Firefox->new(
    launch => 'C:/Program Files/Mozilla Firefox/firefox.exe',tab=>'cur
+rent'
    );

    # tell it to get the main page
    $browser->get("http://search.cpan.org/");

    # submit the query form
    $browser->submit_form(with_fields=>{query=>$module_name});
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