How do I update my Phone (As in the android version and kernel version?)?

[AC Question]

How do I update my Phone? (As in the android version and kernel version?)

I currently am working with an outdated ZTE Model Z750C and its running android 4.1.2 and kernel version 3.4.0-perf root@Linux-server3))#3SMP PREEMPT.
HOW THE HECK CAN I UPDATE THIS PHONE BEFORE IT GETS THROWN OR IN A RIVER? HELP ASAP!!!!!!!

 

[B. Diddy]

Welcome to Android Central! So it's a rooted phone, with a custom ROM? Did you get it this way, or did you root it yourself and install the ROM?

Since it's rooted, check the forums at XDA-developers.com to see if there are discussions about more recent ROMs that you could install.