Hope it's safe if it's definitely for ur device.
Ok let me get into this straight, they havent elobrated things on flashing.
So get into twrp mode and take a nandroid backup for things to be safe. If not familiar with nandroid backup, go to advanced option in that twrp and select backup.
It's best u wipe data & cache before flashing the rom. U can select that option in twrp.
So the next step is to flash the rom, place the rom package in sdcard, in twrp screen select install zip from sdcard and select the rom file.
PS: I am not familiar with twrp coz i ve always used cwm recovery. But dont worry it is also same.
Hit thanks rather than typing it now Free