There's probably a way to export your short animation into animated gif. but if you have Adobe photoshop, you can try following steps:
Create new photoshop document and put each image on separate layer, hide all other layers but the bottom one (nr1)
Now you need to open the animation panel. you can find it in Window > animation
In the animation panel create as many frames as you need in your final animation
Now each frame should show nr1 layer. Select second frame in animation panel and them reveal the correct layer in layers panel. Do the same thing for all your frames.
Finally save the file for web (File > Save for web and devices...)
In the save panel make sure you have selected gif as file format. At the bottom you can choose if the animation plays only once or loops forever and you can also preview your gif. Thats it! Now you got yourself your first animated gif.