Hi, old pedant and dparsons, thank you both for your response.

old pedant, what I want is similar to your friend's flash create image, just that the image keep moving, not stop. but if the image on the flash dynamically change according to different login user, can I use this way? I think the flash should be pre-created, am I right?

Can I dyanmically create flash in javascript or java program?

Thanks!