Total newbie, need some info

Hi karll13, and welcome to AF

I'm afraid it's not that easy. There isn't a generic "android 4.2" that can be installed on any device. Android must be built for the particular hardware. This means that there are two ways of getting an update:

1) when the manufacturer builds an update and distributes it via the net - which is the System Updates menu you have been checking.

2) by rooting the device (gaining administrator access) and installing an update that has been built for the device by an independent developer (a "custom ROM").

The trouble with an unbranded tablet is that 1) may or may not happen - more often not. And 2) depends on people with the skills and interest finding a way of rooting it and building ROMs for it - which is much less likely with an unbranded device than something like a Nexus.

If you can tell us what the device is someone may be able to advise. Or you can ask in the General Tablet Talk forum (or see whether, by any chance, we have a forum for the device). But often with unbranded devices you are stuck with what you have.

 

If it is a tablet there is no way the owner before you could of gotten a working S3 ROM onto it, unless it is infact a Galaxy S3.

IF you go into your about device in the settings there should be some general information that can assist us in learning more about your tablet