I need zombie killing lesons.

Day two: Would you be able to shoot your friend in the head if he turned into a zombie?

Seeing as how I have never shot a damn thing in my entire life and I am scared of guns (due to clumsiness) I am not too sure how that would go.  If I were to get over my fear, which would be probable, see as its kill or be killed, I would kill. Some of my peoples I would have NO problem shooting, while others I would have to think about for a second!
I guess I need some zombie attack survival skills.