Heelp! How much do you pay your nanny and what do they do?

I just want to get a wide range view of the nanny responsibilities and wages. Being a first time parent with no relatives or friends that live near by I am forced to hire help. Unfortunately I am clueless about how all of this works. I wanted to hire through an agency but they want you to hire the person as staff and pay them a high rate for setting you up with this person. For the average person this is insane. I have tried care.com but haven’t had the best luck. How have you dealt with this process?