Function That Loads Users From An Xml File And Authenticates Them. It Works Only On Firefox And Not IE?

My professor asked us to make a webpage that has a user register and login in via a xml document. We can omly use html, javascrip and css.I made a function that loads users from an xml file and authenticates them. It works only on firefox and not IE. This is a problem because i am using ActiveXobject to write to the file.Here is my function that loads xml:

function ReadXML() {
try { xmlDoc = loadMyXML("xmlStudent.xml"); }
catch (objerr) { alert(objerr.description); }[code]....