Unable to enter Recovery Mode

Hello all

Let me start by saying I am unfortunately unfamiliar with Macs in general. I am using a MacBook running OS X 10.6.8 and am trying to wipe the disk clean and start over.

To do this I have attempted to enter Recovery Mode by pressing Cmd+R on startup (which does nothing, and the computer starts as normal), and by pressing Option on startup (which allows me to choose a disk to boot from but not Recovery Mode or any menu options).

I've also looked in Disk Utility, but not only are the Unmount and Erase buttons for my main disk ('Earth') unclickable, there is no mention of Recovery HD or similar in the sidebar-list of disks.

It has been suggested that I try updating to a newer OS and that this might allow me to enter Recovery Mode or do what I am trying to do; unfortunately upon attempted installation of Yosemite an error message appears saying that it is not possible. I am perfectly happy to keep using 10.6.8 if necessary; I would just like to be able to 'factory reset' my computer.

I hope that makes sense. Thanks for your time!

EDIT: I have searched the forum and the wider internet for this sort of thing but have come up empty; if however this question is answered elsewhere (or if this is in the wrong place) please accept my apologies and redirect me!

Message was edited by: svassalos