Hi !! Looks like Mitzi's mom has you covered -
There are several programs to use ....Some people use Photoshop - I use Photoshop Elements 2 and there is some free sites in this thread to learn how to animate.
http://www.yorkietalk.com/forums/showthread.php?t=46790
It's fun once you learn the basics...The tricky part is learning how to layer and get your pictures the right size.