One of the most useful features of Dreamweaver is its extensibility--that is, it offers users who are proficient in JavaScript the opportunity to write JavaScript code that extends the capabilities of Dreamweaver. Many of these users have chosen to share their extensions with others by submitting them to the Macromedia Exchange for Dreamweaver website (www.macromedia.com/go/dreamweaver_exchange).
Your primary browser opens, and the Exchange site appears. (You must be connected to the web to download behaviors.)
For detailed information, see Adding extensions to Dreamweaver.