First start a new file and create a few different layers.
Put something different in each layer; for this demo I'll just make each layer a different color.
After you have taken care of that, open the Animation pallet from the Window menu.
You can add the layers of your Photoshop file to this pallet by clicking the options menu.
From the options menu select the "Make Frames From Layers" command.
Now all of your layers should appear as frames in the pallet. You can adjust the duration of each frame by clicking the time interval below the image, or select all the frames and click on an interval to change them all at once.
Finally, you save the file as an animated .gif by selecting "Save for Web & Devices..." from the File menu. Make sure GIF is selected as the file format and click Save. Have fun!
