You need twrp to update. Once installed, the normal ota system works s it should but it uses twrp rather than stock recovery to install the update. So you may need to enter lock screen password when it reboots to twrp and then it will update, wipe dalvik cache and reboot to system for you.
Thanks for replying , so will need to install TWRP ? so dont need to use PC for future OTA updates
Thanks