I want a career,where do i begin?

right now im a stay at home mom which is wonderful but later i would like to have a career and i would love to be a nurse in labor and delivery and taking care of newborns. I dont have a nursing degree but if i started on one now maybe i would be ready to start working four years from now. where do i start to get a nursing degree and i would need to take night cles and i live in mesa az so there are plenty of schools around here but what is the first degree i need?