In my page editor on the top of the screen i get this message.

Warning: Cannot modify header information - headers already sent by (output started at /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/languages/dutch/define_pages_editor.php:2) in /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/init_includes/init_templates.php on line 36

once i make the neccesary changes to page 5 6 or 7 and i hit the button save my screen goes blank with the following error

Warning: Cannot modify header information - headers already sent by (output started at /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/languages/dutch/define_pages_editor.php:2) in /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/init_includes/init_templates.php on line 36

Warning: Cannot modify header information - headers already sent by (output started at /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/languages/dutch/define_pages_editor.php:2) in /storage/mijndomein/users/143768/public/sites/www.flevoreparaties.nl/webwinkel/admin/includes/functions/general.php on line 21

Somebody who know's what i did wrong?

thanx in advance