upgrade from 10.6.8 to OSX Yosemite

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Upgrading to Yosemite

You can upgrade to Yosemite from Lion or directly from Snow Leopard. Yosemite can be downloaded from the Mac App Store for FREE.

Upgrading to Yosemite

To upgrade to Yosemite you must have Snow Leopard 10.6.8 or Lion installed. Download Yosemite from the App Store. Sign in using your Apple ID. Yosemite is free. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.

OS X Mavericks/Yosemite/El Capitan - System Requirements

Macs that can be upgraded to OS X Yosemite

1. iMac (Mid 2007 or newer) - Model Identifier 7,1 or later

2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) - Model Identifier 5,1 or later

3. MacBook Pro (Mid/Late 2007 or newer) - Model Identifier 3,1 or later

4. MacBook Air (Late 2008 or newer) - Model Identifier 2,1 or later

5. Mac mini (Early 2009 or newer) - Model Identifier 3,1 or later

6. Mac Pro (Early 2008 or newer) - Model Identifier 3,1 or later

7. Xserve (Early 2009) - Model Identifier 3,1 or later

To find the model identifier open System Profiler in the Utilities' folder. It's displayed in the panel on the right.

As of now Yosemite is not available because of the prior releases of El Capitan and Sierra. If your model does not support Sierra then you can upgrade to El Capitan but not Yosemite. If your computer can run Sierra then you can only upgrade to Sierra.

The official list of Macs compatible with macOS Sierra:

2010 or Later

MacBook Air

MacBook Pro

Mac mini

Mac Pro

Late 2009 or Later

MacBook

iMac

Are my applications compatible?

See App Compatibility Table - RoaringApps.

If you never downloaded the installer, it is no longer available. If you previously downloaded it, check your App Store Purchases tab. You can try going to an Apple Store and see if they will give you a copy.

Clarification questions - is El Capitan installed? Why do you need to boot into the Recovery Partition using command - R? Instead of command - R, try restarting with the option/alt key held down and select the Recovery Partition there.

Clarification question - If El Capitan is downloaded on the Mac HD, why do you need to use the option key? Double click on the installer to start it and then let it install.

Why are you trying to partition the hard drive? You posted you already have Mac OS and Windows on the drive.