How to find out what version of Mac OS X you have:
- Click on the Apple logo in the upper left-hand corner of the screen (the Apple menu).
- Click 'About This Mac' in the menu that appears.
- A new window will appear. Underneath the 'Mac OS X text, your version of the operating system will be displayed.
- To exit the 'About This Mac' window, click on the round button furthest to the left, in the upper left-hand corner of the window.
From this window, you can also make sure your software is as up-to-date as possible. Just click on the 'Software Update...' button to ensure you're running OS X with the latest security updates and fixes.