HTC One Help - System Update

Morning all,

I'm just after a little bit of help with my HTC one. I'm new to android so I have followed a guide on how to unlock the bootloader, root my phone and install a custom recovery using TWRP from your website. I wanted to install the google edition on my htc one but I couldn't get s-off.

Anyway I still have the original stock operating system on my phone now I haven't flashed a custom ROM or anything but I have a system update available to me but I can't install it, everytime I click install now the phone reboots into TWRP and i'm not sure how to install it. Could anybody help please?

Cheers