Function keys on MacBook Pro

I am trying to get the function keys to work with my weapons. I can not find our how to make them active. Any ideas?

You need to press the fn key in the bottom left corner of your keyboard or go to system preferences then select keyboard and mouse then the keyboard tab and tick the box marked "Use all F1, F2, etc. keys as standard function keys" this will then switch the behavios of your keys so you'd have to press the fn key if you want to use the keys to turn up your screen brightness/audio op etc.

Thank you very much. I am looking forward to trying this later