htc 816 g octa core sowftware issue

hello friend i m new in flashing , rooting booting and in applying custom roms .
all those who having htc desire 816 g(mediatek device) , facing the same problem , its software.:confused:
mobile works on 4.4.2 bt i want to change it to lollipop , bt hard to get custom rom fr 816g.
someone help me and suggest me rom which applicable for 816g. (em dying for lollipop):crying::crying:
pls pls pls