Photoshop CS2 is an older edition of the famous Adobe product, which as of mid-2010 was up to version CS5. Major changes took place between the CS2 and CS3 versions. One of these has to do with the way the program generates animation. In Photoshop CS3 or later, animation is done entirely within the Photoshop application. However, in Photoshop CS2 it was done by working in concert with ImageReady, which was a companion program bundled with Photoshop. Although it is not quite as user friendly this way, you can still produce quality animated GIFs in Photoshop CS2.
Load the images that you want to use for your animation onto your computer. Save them all to the same folder. It is best to number them in the order you want them to appear in the animated GIF.
Open Photoshop CS2. Select "File" from the menu and choose "New". In the dialogue that appears, enter the pixel width and height for your animation. Name the document "animation 1" (or whatever you like) and click "OK".
Select "File" from the menu and choose "Open". In the dialogue that appears, go to the folder you saved the images to and open the first one. Right-click on the layer in the "Layers" palette and choose "Duplicate Layer". In the dialogue, choose the "animation 1" document as the "Destination". Click "OK".
Repeat step 3 with all of the images you want to use in the animation. Then click on the "ImageReady" button at the bottom of the toolbar. This will open your layers in ImageReady.
Go to the timeline in ImageReady and at the bottom of each frame enter the duration you want. Then select "File" from the menu and choose "Save as Optimised". Name the file and save it as a GIF.