If it comes off, do not worry.
There is a keyway that only allows it to go in the correct way!
Kinda fool proof.
The only problen I had was that the Keyway had worn off, and I had to get another from Autozone (Yes, I was shocked they could get it!).
Just take your time, and if you have any mechanical abilities, you will be fine.
If I may ask, what is your locations?
If you are near by and need a hand you can let me know.
Joe