My b2evolution Version: 2.x

Im using b2evo v.2.4. To translate it on polish language I used v.0.9 files. I had to made some additional work on the file. But every time I try to edit and save file (even just save without changing anything) I see this text on top of my site:

Warning: Cannot modify header information - headers already sent by (output started at /public_html/locales/pl_PL/_global.php:1) in /public_html/inc/skins/_skin.funcs.php on line 379

If I upload original file (which I didnt edit) text disappared. I tried to edit files on two computers, with notepad.
How should I do this right?