Theres many programs now that allow simple animation editing. Even the latest version of photoshop has support for animation. Macromedia Fireworks is a web graphics program that I find great for gif animation. Theres also Ulead animation shop and paint shop pro. just do a search and find youself some software, theres probably even some free software out there too. All you need is a minimum of 2 frames 1 normal and 1 where the picture is changed, when the frames are played back it appears like the picture is moving.
Have fun.