Write To XML On Server

Hi
I am working with an XML doc stored on a server…

The contents of the XML read as follows…

I am looking for a way to update the XML using Applescript.
Eg Update the value of “CurrentUserName” to “Daniel”

I have tried the following but Im getting errors.

tell application "System Events"
	
	set theXMLFile to "http://192.168.10.5"
	
	tell XML element "BrightSignUserVariables" of contents of XML file theXMLFile
		set value of XML element "CurrentUserName" to "Test"
	end tell
	
end tell