use WWW::Mechanize::Firefox;
use Data::Dumper;
use utf8;

my $mech = WWW::Mechanize::Firefox->new(
    launch => 'firefox',
	autoclose => 0
);
$mech->get( 'https://www.zentrada.de/login/index.cfm' );

$mech->form_number(2);
$mech->field('ff_email', 'xxxx');
$mech->field( 'ff_passwort' , 'xxxx');

$response = $mech->submit();