OS upgrade from 5.0 lolypop to 6.0 orhigher for Samsung Galaxy Note 3

[Astronaught15]

I have been using samsung galaxy note 3 . However, of late i am unable to use few services as my phone is having OS  5.0 . 

When tried to update my software, it says its updated

Can someone help me to upgrade my OS from 5.0 to 6.0 or higher .

 I will appreciate .

[vkeshav]

awesome phone used it almost 4 years...camera quality was good