Using events with the Application object (Word) | Microsoft Learn

I have followed the steps declare object variable

Public WithEvents App As Word.Application

I have written an event:

Private Sub App_DocumentChange()
MsgBox "application change document app ran "
End Sub

I have written the declared object

Dim X As New EventClassModule
Sub Register_Event_Handler()
Set X.App = Word.Application
End Sub

I do not understand how to Run the Register_Event_Handler procedure above.

nothing seems to work