If it is a one-page app then as you select EditText in the Designer and generate it as a member of the app, it is initialized spontaneously.
Otherwise, you can create it programmatically as follows:
Private EditText1 as EditText
EditText1.Initialize("ed") 'Ed is the event name
In this case you have to initialize it manually as any other control.
then you can use 'ed' for different edittext methods as ed_TextChanged