Thank you very much for your help. I've got to set it up.

I use CPANEL as domain control interface, and there is Cron Jobs there to set up this kind of activity. After several emails sent to host support, I found out that it works with the line below:

*/5 * * * * php /home/mydomain/public_html/moodle/admin/cron.php

I hope that this post can help others that host their domains in hosting servers with Cpanel.

Once more time, thank you very much.

Giovanni