Upgrade android 4.2.2 to 4.4 (MHTMID-B718DC8 DualCore-A23)
There are a lot of custom Android ROMs out there, you need to find one that was made for your specific device. XDA-developpers and FreakTab are good places to look. Flashing requires a few utilities, but it is a fairly straight-forward process. Whomever made a custom ROM for your device would tell you the specific flashing procedure and utilities for your tablet.

Your first step is to find a custom ROM that was made for your specific tablet. I still run custom KitKat ROMs on a couple of old phones.