Hi Herb,
What file type are you trying to upload? I don’t remember off the top of my head, but I do believe the forum software only accepts jpg’s or png’s (maybe gifs too). I just tried with a png – and that worked.
If you want to show animation, you can upload your file elsewhere and link to it here. Do you have somewhere to put it? Otherwise, you can send it to me and I will upload it. Youtube links work too by the way (if I’m not mistaken).