order number copy somewhere

[popustda]

Hi,
Can anyone tell me how to make an ORDER # which customer receives in an email (header) and which also shows inside the email to put it to show also in part od email where customer writes comments?
Example: If a customer makes an order "ORDER 100" i want this also to show in comments part of an email.
pictures attached

thanks

[Basara]

Hello.

You need to edit few files see post