Start with http://www.JUnit.org. They have a "getting started" page that includes the famous "Test Infected" paper. ObjectMentor has a number of Robert Martin's "crafstman" stories and the "bowling game" diary which illustrate test first coding and refactoring.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi