changing permission of files (php+windows)

Hi, I have a problem. I'm running an Intranet environment in PHP on IIS. I'm uploading files through a php-script. The files are only readable when I'm logged-on in my windows account. Other windows-users can't access or read the files. How can I change the permission of those files - using my script - so that other users can access or read the them as well? Thanks in advance, ffox