So I got a link, and I know it should work because it is on apple's website, but when I download it, it says that it can not be opened. On the site it said it was for a macbook OS X and some numbers after it. I'm completely ignorant when it comes to macs, so I don't know what my mac is. All I know is that it is a macbook pro because it says so under the screen. Also, something called "Snow Leopard" is mentioned quite a lot. I don't know if my computer has it, and wether I need it for the download to work. How do I know if i have it? How do I know if my computer is a OS X and whatever number? And most importantly, why isn't the download working?