Help me please.. Just got the chinese version n1 and stupid enough i updated to 5.1.1

ANYONE CAN HELP ME PLEASE.. I JUST GOT THE CHINESE VERSION N1 AND STUPID ENOUGH I UPDATED TO 5.1.1... AND I am very rookie on rooting... is there anyway i can downgrade the android back to 5.0..
And also step by step, anylink that you guy posted before I will read!!! but... please... help me... teach me how to downgrade back in order to root....