Ben bu formatta ile xml depolama var

<Contacts>
     <Contact>
         <![CDATA["Some HTML"]]>
     </Contact>
     <Contact>
         <![CDATA["Some HTML"]]>
     </Contact>
</Contacts>

I am using XMLHttpRequest to read the data and put it inside a "div" on the page. Now I make some changes on it via JavaScript and I would like to know how can I update the changes made back to the XML file from where I took the data. I've been googling a lot but I have problems understanding those forums because they are not describing examples similar like mine.