From EduTechWiki - Reading time: 4 min
This entry is part of the Flash tutorials.
Layers help you deal with more complex Flash projects. Working with layers has several advantages:
The layers tool is part of the Timeline panel.
The layers tool is in the left part of the timeline. Annotations in the following screen capture highlight a few functionality we will further explain below.

To draw, paint, or otherwise modify a layer simple click on the the layer name in the Timeline to make it active. A pencil icon next to it indicates that the layer is active.
When you create a Flash document, it only contains a single layer, i.e. less than you need.
To create a new layer, either:

As soon as you create a new layer, you should give it meaningful name. Right-click on its name (something like Layer 2) select Properties and change the name. Alternatively, to display this properties panel, just double-click on the layer name.
To delete a layer and its contents: Right-click->Delete Layer. You also can lock/hide other layers with this menu. Before you delete a layer make sure that you save its objects if you plan to keep them. You can insert them in the library as symbols or copy them to another layer.
Click on the dots below the appropriate hide/lock/display icons in the panel to apply locking/hiding/displaying to a single layer, or on the icons themselves to apply an operation to all layers (e.g. lock them all).
TIP: Always lock all layers and then just unlock the layer on which you are working. This way you can prevent yourself from making mistakes.
To move a layer in the stack simply grab it with the mouse and drag it up or down. Position of the layer has an influence on the order objects are drawn. E.g. if a moving object should pass in from of a tree and it doesn't, then drag the animation layer up or down.
Drawing order depends on the load order defined in the Publish Settings (File menu)
The following screen capture shows hidden and locked layers:

Once your documents get really complex, you can organize layers into folders, e.g. one folder per task: Static objects, animations, background etc.
To create layer folders, either:
You then can drag around layers. Hiding, locking etc. works more or less like with folders (try it out ...)
However, at some point you also will have to decide whether you really want to work with an "everything is in the main time line model". Consider organizing and planning your project with embedded movie clip objects (see the Flash embedded movie clip tutorial). Putting everything in the main time line is like programming with "goto's"...
Once your animation gets bigger, you most certainly should break it down to several scenes. There is no urgency to work with scenes if you are new to Flash, but you should know about this now. Scenes are played in the order you defined them.
One advantage of using scenes is that you can just test a single scene (menu Control->Test->Scene).