OS X really old update needed.
I am using and iMac. I believe I am running a very old OS X software. It does not say Leopard or Lion or 10.anything. How do I go about getting updated to the most current system update. When I run software update, it says all is up to date. I bought this computer a few years ago from a friend, but is probably 6 years old I would guess. The kids are having trouble playing basic online games such as Minecraft and I think it is because the software is so far out of date. Please help for the kids sake!
iMac, Mac OS X (10.7.2)