Add a Site to Apache2 Using a Different Port

I have inherited the management of an old server. It seems that there is an intranet site configured to the port 80. In that server it seems that there is also installed vtiger version 5.4italian I would like to publish vtiger site to the port 90 an try it out. the beginning page should be: /var/www/vtigercrm504ita/index.php Can you point me to a guide that tells me what files do i need to edit? this page is not telling what files do I need to edit. i tried:

     nano /etc/apache2/sites-available/vtiger.conf

    Listen 90

<VirtualHost *:90>

        ServerName localhost

        <Directory /var/www/vtigercrm504ita>
                AllowOverride None
                Require all granted
        </Directory>

        DocumentRoot /var/www/vtigercrm504ita

        ErrorLog ${APACHE_LOG_DIR}/vtiger.error.log
        CustomLog ${APACHE_LOG_DIR}/vtiger.access.log combined

</VirtualHost>

but if I go to ip:90 i get ERR_CONNECTION_REFUSED instead of the page /var/www/vtigercrm504ita/index.php