Relaxer question?????

so this is my first time putting on a no lye relaxer and i am scared because i heard it will take away your natural hair or it will damage your natural hair and i was wondering does it really if you like put it on 2 times for the next 7 yrs because i don't want it to take away my natural hair i don't want it to damage it and if it does i heard you have to cut where you relaxed and i put the relaxer on my whole head and was wondering if that's true do i have to shave off my whole head sorry but this is new to me i just tried it out and am kinda freaking out that that was gonna happen if you put on a relaxer