Changing ROM HELP

Hi guys I wanted to tell you that I have a rooted LG G3 D855 and I was running Candy ROM when I made up my mind and wanted to flash Xtra Lite 3.0 for D855. I read the instructions and but I when I flashed it failed. I couldn't understand what exactly wrong I was doing !! Secondly I read not once but many times that we have might have to flash kernel for xtra lite 3.0. There was link which had many kernels and I got puzzled which 1 to flash for my LG G3 D855. :confused:
Well then I flashed Blisspop ROM as I got frustrated and things started to work. I really want to flash xtra lite 3.0 but I am not doing it the right way. I tried to Google but I was very uncertain and wasn't able to understand what I should do?
I was getting this message after I was flashing xtra lite 3.0 via TWRP "error executing updater binary in zip twrp"

Would it be nice if someone could guide me step by step as I want that ROM for my device ! I am sorry that if some of you feel I am asking too much...