you dont need root to install
if you installed ioroot, navigate to the folder, plug phone in with debugging enabled and type adb devices.
if your device is listed, unplug phone, drop the update file in the ioroot folder, then power phone off
power phone back on by holding the volume down, and then hold power button down. once the lg logo comes up release the vol down and then push it back down again. it will say loading recovery mode.
when in that, down arrow to adb sideload. tap the power button on that
then plug phone into computer, and open cmd, navigate to ioroot
type adb sideload update.zip (i renamed my file update.zip to make typing easier)
it will update the phone.
dont be scared, dont root just to update thats dumb.
if i bricked your phone im not responsible, abd sideload a stock file is almost impossible to brick tho