Updating Supersonic SC-91MID

I'm new to android, and until just a few hours ago I've only ever used apple devices. Anyway, I was wondering if anyone has info on manually updating tablets. This device has 4.0.4 and I'd like to update to 4.2 but it won't automatically update. I emailed the company's support services and they said I could try updating manually but they can't guarantee success, and they won't tell how to update manually. I've spent years jail breaking my apple devices and I'm excellent with computers so I can follow simple or complicated instructions but when it comes to finding info about my new tablet and android I've not been successful. Any help would be greatly appreciated, and if more info is needed just let me know.

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