tep = 1 > You Need A Custom Recovery Installed On Your Device Twrp 2.8.7.x recommended
Step = 2 > Backup Your Current Rom and all data With Recovery Mode
Step = 3> Download The Rom &Copy itTo Sd Card
Step = 4> Turn Of Your Phone .
Step = 5 > Turn Your Phone RecoveryMode By Volume Up + Power .
Step = 6 > Wipe advanced wipe ( system/ data/ cache/ dalivak cach )
Step = 7 > Go To Install Navigate To Miui 7Rom Zip
Reboot And Enjoy