Using Layers - MACROMEDIA FLASH 8-GETTING STARTED WITH FLASH Getting Started

To change the length of a tweened sequence, drag the beginning or
ending keyframe left or right. To change the length of a frame-by-frame
animation sequence, see "Creating frame-by-frame animations" in
Using Flash.
To add an item from the library to the current keyframe, drag the item
from the Library panel onto the Stage.

Using layers

Layers are like transparent sheets of acetate stacked on top of each other on
the Stage. Layers help you organize the artwork in your document. You can
draw and edit objects on one layer without affecting objects on another
layer. Where there is nothing on a layer, you can see through it to the layers
below.
To draw, paint, or otherwise modify a layer or folder, you select the layer in
the Timeline to make it active. A pencil icon next to a layer or folder name
in the Timeline indicates that the layer or folder is active. Only one layer
can be active at a time (although more than one layer can be selected at a
time).
When you create a new Flash document, it contains only one layer. You
can add more layers to organize the artwork, animation, and other
elements in your document. The number of layers you can create is limited
only by your computer's memory, and layers do not increase the file size of
your published SWF file. Only the objects you place into layers add to the
file size. You can also hide, lock, or rearrange layers.
You can also organize and manage layers by creating layer folders and
placing layers in them. You can expand or collapse layer folders in the
Timeline without affecting what you see on the Stage. It's a good idea to
use separate layers or folders for sound files, ActionScript, frame labels,
and frame comments. This helps you find these items quickly when you
need to edit them.
In addition, you can use special guide layers to make drawing and editing
easier, and mask layers to help you create sophisticated effects.
For an interactive introduction to working with layers in Flash, select
Help > Flash Tutorials > Basic Tasks > Work with Layers.
Getting to know the workspace 61