Updating an XML file with PHP

Hello all,

I am completely new to PHP and therefore I have troubles solving a problem I have updating a XML file with a PHP file involving a text field and a submit button.

I include in attachement to this message my two files so far : an XML file called “news.xml” and a PHP file (the beginning of it…) with my text field and a submit button with the id “envoi”, both in a table with a invisible field called “action” near the submit button with the value “ecriture”.

What php code can I add to update my xml file? And where should I place the script?

Thank you in advance for your precious help.