Leader election in zookeeper

I have 15 machines connected through a network. out of 15, zookeeper servers
are running in three different machines and I have to select a leader for
this distributed systems. My doubts are

1. For the election, 3 are zookeeper servers here so whether they also
contest in this election.
2. How the election will be held. can u explain with each steps.
3. After electing a leader, how a node knows it is the leader.
4. Also can u explain how zookeeper co-ordinates this service simply.