Use this way
to show your own headline news in other web site use backend.php. normally it's available in the main folder where u placed for EX: index.php. just give a link to that file to other people who want to show ur headlines news.
and if u wan to show other web site headline news in ur web site just find their RSS/XML address.
in PHP-Nuke it's special, u can use their backend.php file. usually they placed a link to that file at the end of page.
Have Fun
Mohammad