In first place, you need to know how to get the credential for WNS OAuth authorization.
Please follow this link for more info.
You need to include php script in your file or include it with PHP require\include[_once] functions.
After you got the SID and the client secret from the Windows Developer Dashboard, you need to set the class WindowsNotificationClass static attributes:
$SID = <YOUR SID>
$ClientSecret = <YOUR CLIENT SECRET>
Now you’re ready to use the WindowsNotification object!
However, the WindowsNotification object support all the custom header for WNS request (X-WNS-Tag, X-WNS-SuppressPopup, etc.).
It’s your task to use these Settings Object’s attributes (see this) in the best way for the scenario you have.