I would start with the Simulink examples on the product page. There's also the intro to simulink webinar in the webinar sections. Take some time to first understand Simulink before moving to stateflow. For stateflow, there are similar getting started videos on the product page that should help you learn.
Once you've watched the videos, it will make following examples easier. The difficulty with Simulink and Stateflow written examples is the nature of graphical modeling. It's tough to illustrate how you get from A to B to C without the help of video, but there are better examples if you search through these sites.