Preview Animation
To preview the animation, click the Animate toolbar button, or Animation -> Animate menu item.

To stop the animation, click the Stop toolbar button, or Animation -> Stop menu item.

Preview on web page
You can view your animated GIF directly on a web page to see how it looks with a specific background.
To preview your GIF on a web page, click Tools -> Preview on Web Page menu item. Preview on Web Page dialog will appear.