For an animated sprite in PCX, BMP, or TGA format, place the single animation frames beneath each other in the image (as in a horizontal film strip), and give the number of frames by adding a '+n' to the file name - see the example explo+7.pcx in the template folder.
See also entity.frame and entity.next_frame.
If you want an animated crowd you can place several images like said above (you need the images so you can eventually print from a short film at diferent times).
Also in the aum or resources links probably you will find a good example of that, i dont know for sure. If you search the forums you will find information about that too.
