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.