It depends on what type of animated image you want to make.
GIFS (or animated images) are basically mini movies, in .gif format.
the best way I find is to either you moive maker (with each image being a "slide") then save the movie, then run that movie though one of the various "movie to gif" websites nocking around,
or to use powerpoint and do the same.
Their are other ways to do it using fancy software, but those are complex and expensive.