Power of attourny question... very very important!?

I'm 18 years old and My father is in ICU at the hospital that i work at but he is incpacitated and is unable to make any decisions, and he and my mother are going throug a divorce and my family wants me to be his Power of Attourny but i dont know exactly what that is, how i become it or anything like that, I know this is what he wants also, he told me he wanted my mom out of everything and she said she would help me but she doesnt want to be his PoA and i am his only living relative over legal age. any advice would be GREAT!