https://support.microsoft.com/en-us/kb/258824 http://www.wikihow.com/Change-the-Keyboard-Language-of-a-Mac Everything is there, step by step. Good luck!

To write typical Polish letters you should switch your keyboard from your native language to Polish language (Polish used by programmers). You can usually do that in the control panel. To write for example ą you should use two buttons together - a+altgr, ą=a+altgr ę=e+altgr ń=n+altgr ź=x+altgr etc. To write big Polish special characters you need use Ą=A+altgr+shift. The second way is to use system keyboard.