this totally depends on the make and model of your device -
http://www.cyanogenmod.org - generally covers options for a lot of android devices and is fairly simple as well as giving the option to upgrade to latest android release in most cases
i have to add this disclaimer - if you are unsure then dont proceed - in most if not all cases you void any warranties you may have on the device and do also risk "bricking" the device and making it useless, so only go ahead if you are comfortable with the process
you should also note that whatsapp will only work on a single device at a time, i tried running whatsapp on my mac via the android emulator and it stopped my iphone from working with it, when i signed back in to iphone it stopped the android emulator from working and you have to go through the verification process each time you reconnect the app on different devices
