Really helps when you tell us what phone you have... I am assuming it's the HTC Vivid (or Raider/Holiday)? If so, there are definitely no official updates to Kit Kat. Your best bet would be a custom rom like CyanogenMod.
Please read through the thread to understand what does and does not work. These roms are vastly different than the one you have installed now. The devs have install instructions included. Basically the same as any other rom for your phone. If you are S-On, you have to fastboot the boot.img.
http://forum.xda-developers.com/show....php?t=2437705 (use this tool to root, install recovery, etc)
http://www.addictivetips.com/mobile/...voked-forever/ (do not follow guide, just for info)
Kit Kat roms:
The complete steps really depend on if you decide to go S-Off or not .S-off is a bit more of a pain to set up, but makes it easier to flash roms, radios, and firmware. S-On is easier initially, but you will need to take the boot.img (kernel) out of the rom zip you are flashing and install it via fastboot method or, once rooted, via an app like Flashify. You should read up on the pros and cons of S-On vs S-Off to make sure you know what it entails. Also, none of the KK roms are considered stable for your device. That might mean it can have glitches. It might not have some functions working that are necessary, or the minor bugs might not affect how you use the phone at all. Everyone uses their phone different and different phones run different software better or worse. You won't really know until you get it set up and test it.
If you need adb and fastboot: http://forum.xda-developers.com/show....php?t=2317790
I don't mind helping, but it is very important to read as much as you can to understand what changes you need to do and how they will affect the phone. There is PLENTY of info on your phone here on XDA. You should browse through some of the guides and info in the General section and the Development section.