I can't seem to be able to download Mac OS X Yosemite

Hi,

I am working on a Mac OS X

processor 2.66 GHz Intel Core 2 Duo

Memory 2 GB 800 MHz DDR2 SDRAM

version 10.6.8

I'm not having much success on downloading the Yosemite .. Please be e-z on me .. it literally has to be broke down in elementary format .. I'm not that computer friendly .. and if I get frustrated .. I cry ..

Thanks for any help anyone may have