So to start off, let’s create our landscape for the animation. The landscape will remain static for the entire animation; in keeping with the theme, we can work with something simple: a city skyline against a dark night sky.
Open a new document in Flash. First we’ll set the canvas color for the animation; since the main base of the scene is the night sky, we’ll pick a dark blue by going to Modify -> Document (or hit Ctrl+J for a shortcut) and selecting a dark blue background color using the color picker; I’ve chosen an indigo shade.
While you’re there, change the document size from the default to a 320w x 240h, to use a standard 4:3 web production aspect ratio. Leave the frame rate at 12 fps.