The "Login With Facebook" text is defined in the language files. We don't distribute a Turkish language file by default, but you can create it by copying:
/languages/en-gb/en-gb.com_jfbconnect.ini
to
/languages/<your_language>/<your_language>.com_jfbconnect.ini
Once there, you can change all the language strings to match your language. You'll want to use the language code that you have set in Joomla for the file name above.
Hope that helps, but if you have other questions, just let us know.
Facebook Login Button Language
