\\o//Hello tigermuller. To find out what Mac you have go top left of screen click on apple, then in list click about this mac.
This will tell you Mac system, at bottom of this box click more info, this will tell you what mac you have.
Now to run permissions, open your hard disk click on Applications, then in that list find Utilities and click it, in there is Disk Utility. open it and click on your Hard disk, then click on verify Disk Permissions, is some come up in box to be fixed click on repair underneath when finished Verifying.