Start with watching or reading some of the videos or articles that Neal Ford has published on the subject. Here's a case in point: GOTO 2013 - Emergent Design, Neal Ford.
As he suggests in the video, you can read more about it in IBM's developerWorks library using this link: https://www.ibm.com/developerworks/views/java/libraryview.jsp?search_by=evolutionary+architecture+emergent+design.