Caution: I am not liable if you screw up the process for your device or if you need to un-root it for whatever reason. Follow these steps carefully! Make sure to do some research first before rooting your device: make sure that it is important enough to risk voiding warranty.
Step 1: First Things First...
Step 2: The App
Step 3: Get the Drivers
Step 4: Get the Root Files
Now, plug in your phone to the computer via USB. In the USB settings set it to charge only, that seems to help with reliability. The computer might say "installing device drivers". Let that finish.
Step 5: Fun With Command Prompt
Open command prompt (Start menu search cmd or Ctrl-Windows key and type cmd)
Type this in the command prompt (NOTE: there is stuff in between but these are the only lines that you type and press enter on, including the /data/tmp/install-su.sh at the bottom; see the picture for clarification.)
adb push photon-torpedo.tar /data/tmp
/bin/tar xf /data/tmp/photon-torpedo.tar
You will get an error message after you type /data/tmp/photon-torpedo.sh
The error message will say this.
ERROR: ld.so: object 'libpcprofile.so' cannot be loaded as audit interface: unde
fined symbol: la_version; ignored.
Fatal server error:
Server is already active for display 0
If this server is no longer running, remove /tmp/.X0-lock
and start again.
Please consult the The X.Org Foundation support
at X.Org Wiki - Home
ddxSigGiveUp: Closing log
bash: groups: command not found
All you do now is simply type /data/tmp/install-su.sh and hit enter. Check the picture to see that everything is in order!