1) Download the SuperSu App from the Xda Web SIte
h t t p ://download.chainfire.eu/641/SuperSU/UPDATE-SuperSU-v2.40.zip
h t t p ://download.chainfire.eu/644/SuperSU/BETA-SuperSU-v2.42.zip
Copy it to your SD card .
2) Go into recovery modded
Select SuperSu v.xx and install
Reboot into android S.O.
You should see the app installed Super Su.
3) Install Busybox (from files or from GooglePlay store)
open the app and give the right Su power and wait for it's scan
4) Install the binary from the Busybox menu' "normal install"
After correctly installed the binary ...Reboot the phone
And you will have your rights as a Root