Thread:Extension talk:Header/Create header.php

Can I just create the file "header.php"?

I did that but I am just getting:

Warning: Cannot modify header information - headers already sent by (output started at .../wiki/extensions/Header/Header.php:6) in .../wiki/includes/WebResponse.php on line 37

I read that this means there is a problem with "header.php".

I created the file with Notepad++, not with Windows Notepad to have the right "coding"

and

there is nothing (even not whitespace) before the <?php tag

Can anyone help here? Thanks.