Animation

I have GIMP 1.2, and I am trying to do some animation I have 14 different pictures that are slightly different from one another, but the first and last are very different. What I want to know is how can I put all 14 images together so that it is in motion from one picture to the next in a gradual change? I looked in the memories and di not find anything, and so I am throwing the question out there with hopes that some one can help. If anyone has any suggestions that would be great!