OS or Firmware is pretty much device specific. You will need to get an upgrade ROM from your manufacturer, or from the Android community (assuming someone has taken the trouble to modify a ROM for your device). That is one reason I chose a WITSA81G - good manufacturer firmware support as well as community. Also it is easy to reflash from the SD card, so danger of 'bricking' the device is small.
This is a 7" MID Android tablet which was running 1.6 I believe. I tried to upgrade it and the firmware was apparently overwritten but not success because now the tablet is dead. Any way to save it?