hi friend ..
i'm also new about rooting hTC (1st time).i'd like to help, but not good enough on explanation ..i root my hTC One on day 2nd bought it.Might some help from youtube and xda topics about unlock bootloader, s-off & rooting.
after u done unlock bootloader, just download twrp zip or cwm zip..extract it copy twrp file (img) on fastboot folder (on pc drive with fastboot files for unlock bootloader process).
right click img file to open as cmd.Then type "fastboot flash recovery recovery.img" then press enter..if u see word just like okay u can go back to bootloader mode, select recovery if u see word on top of screen while htc booting mode that's mean u already done flashing recovery.wait just 2 second, twrp should appear..u should download superSU or super user early put on ur sd then u flash it use twrp..check ur root status use root checker or titanium backup.lastly u tap on superSU or super user icon to update binary (for this method i'm not sure u need to update or not) might somebody got any best answer..
sorry for bad english & too simple methods.
Sent from my HTC One using xda app-developers app
My current device : hTC One Black 32gb stock
Device history from 2011 until today :
hTC Flyer 32gb by Maxis, Galaxy Ace 2 GT-i8160, iphone 4s 32gb by Maxis, Galaxy W GT-i8150 , s.e CK13i, )s.e Xperia Ray, hTC Desire C by Maxis, iphone 4 16gb (Locked by AT&T), Blackberry Bold 3 9780 (use for 2 days only), Galaxy S3 i9300, ́phone 3GS 32gb, Nokia Lumia 520, Samsung Galaxy S4 i9500 16gb Black mist..