Problem is, that all online tutorials are based on English version. So I want to change my UI language.
Go to where you installed Photoshop -> Locales -> language folder -> Support Files
Then find file "tw10428.dat" and change it's extention to ".bak". Restart Photoshop.
C:\Program Files\Adobe\Adobe Photoshop CS6\Locales\pl_PL\Support Files
Now, because Photoshop cannot find your localized language, it will display menus in English.