Select one or more layers in the Storyboard or Timeline. Then choose Animation Assistant… from the menu to open the assistant.
The assistant lets you apply animations to the selected layers by choosing from several options. You can choose animation options for different types of images, video, and text layers separately, because for each type slightly different settings are most useful. Usually you choose your settings in this assistant once (according to your personal likes), and then you leave those settings untouched.
First you need to choose the animation speed with this slider.
For regular images zooming (in, out, alternating) makes most sense.
Widescreen panorama images are best panned (left or right).
Check Fit to Stage if you want to show the whole panorama at once – panning animation is not available in this case and the image will be shown letterboxed on the Stage.
Square images can be zoomed (in, out, alternating). Since the image composition in square images is usually important, it make sense to check “Fit to Stage” to show the whole image.
For vertical images you have several options. They can be zoomed (in, out, alternating) or panned (up or down), but not both at the same time. Uncheck “Fit to Stage” if you want to avoid the pillar-boxing effect (i.e. showing background color to left and right of the image).
Video layers can be zoomed (in, out, or alternating), but since they already contain motion, this is not needed in most cases. If the aspect ratio of the movie does not match the aspect ratio of the Stage, you may want to check “Fit to Stage”.
Text layers can be zoomed (in, out, or alternating). Long texts can also be scrolled. If the text is higher than the Stage then it will scroll up, like the traditional scrolling credits animation. If the text is a single line and is wider than the Stage, then it will be scrolled from right to left, creating a “stock ticker” effect.