You can easily define a timeline with the Timelines panel. Each part of the Timelines panel controls a different aspect of the timeline.

To open the Timelines panel:

1	Select Window > Timelines panel or press Shift + F9.
2	Right-click (Windows) or Control-click (Macintosh) the Timelines panel to open a context menu that includes all of the relevant commands.

Playback head shows which timeline frame is currently displayed in the document. You can view different frames of a timeline by dragging the playback head through the frames.

Animation channels display bars for animating layers and images.

Animation bars show the duration of each object's animation. A single row can include multiple bars representing different objects. Different bars cannot control the same object in the same frame.

Keyframes are frames where object properties (such as position) are changed. Dreamweaver calculates intermediate property values for frames that lie between keyframes. Small circles mark keyframes.

Frame numbers indicate the sequential numbering of frames. The number between the Back and Play buttons is that of the current frame. You control the duration of animation by setting the total number of frames and the number of frames per second (fps).

Behaviors channel is where you add a behavior you want executed at a particular frame in the timeline.

 
Playback options
Timeline playback options allow you to view an animation one frame at a time in the Document window. Other playback options affect how an animation plays when the web page is loaded in a browser. Use these options to set whether the animation automatically starts and to set whether the animation repeats or loops.

Rewind moves the playback head to the first frame in the timeline.

Back moves the playback head one frame to the left. You can play the timeline backward continuously by holding down the Back button.

Play moves the playback head one frame to the right. You can play the timeline continuously by holding down the Play button.

Autoplay sets a timeline to begin playing automatically when the current page loads in a browser. Autoplay attaches a behavior to the page's body tag that executes the Play Timeline action when the page loads.

Loop sets the current timeline to loop indefinitely while the page is open in a browser. Loop inserts the Go to Timeline Frame behavior in the Behaviors channel after the last frame of the animation. Double-click the marker in this frame to edit the parameters for this behavior and change the number of loops.