use strict;
use WWW::Mechanize::Firefox;

my $url   = "http://www.decodethis.com";
my $agent = WWW::Mechanize::Firefox->new(
    activate  => 1,
    autoclose => 0,
);

my $sn = "1D7HU18D14J230995";

$agent->get($url);
if ( $agent->success() ) {
    sleep(2);
    print "Retrieved $url\n";
    $agent->form_name('Form');
    $agent->field( 'dnn$ctr373$VINBox$tbVIN' => $sn );
    sleep(2);
    $agent->submit_form( form => $agent->current_form());
}