Atheism is simply the rejection of the antiquated and medieval belief systems that people still cling to and the acceptance that it doesn't really matter if there is a God or not, simply that you need to live your life as well as you can. You don't need to do anything except live your life.

Often religions are tied to regional culture so it can be hard to abandon faith if you have a religious family. Perhaps keep it low key and don't be too vocal, at least at first. If your family go to church/mosque/temple/whatever it can be easier to go along with it until you can break away. Perhaps with your own family or new life somewhere.

Many people including the slightly odd responder above will claim that atheists are deranged and immoral, however, take a look at some of the acts of the faithful happening every day around the world and you'll see... They're not athiests are they?

Read: the God Delusion by Richard Dawkins and check out some Christopher hitchens. God is not great to start.