how to get snow leopard 10.6 on black macbook?

I have a 2008 black macbook that is stuck on 10.5.8. I tried to download things to update to yosemite however it needs to be on 10.6 to work. This is frustrating because I cannot download and use update browsers, final cut pro x or microsoft word packages. I downloaded snow leopard, but whenever I try to open it I get "This update requires Mac OS X version 10.6." which is what I am attempting to update to so I'm lost on that. How can I get snow leopard 10.6 on this early 2008 black macbook?