Use the link below for additional help:
http://www.youtube.com/watch?v=DRFyNHdVgUA
http://www.youtube.com/watch?v=70NQ3ISYihw
http://www.youtube.com/watch?v=Xne6Hv9useE
http://tutorial.math.lamar.edu/Classes/CalcI/AreaBetweenCurves.aspx
Examples:
http://www.dummies.com/how-to/content/how-to-find-the-area-between-two-curves.html