I'm so sorry I missed your question on the last page! Anyway, the format should be a gif. To put gifs in a post just do it the normal way you would for a still image. Export it from the program you're using so that it works for web devices, upload it to a photo sharing site then copy the link into a post.Following up on my previous question, what is the most common format to put animated images on the forums--something like iDrops' avatar or King Sora X's signature? How exactly do you include those in a post, signature, or elsewhere?
As for submitting animated sigs, I personally don't mind since I was planning on making it a theme anyway, so you can submit an animated sig in any sotm. The only problem with animated sigs that I've found is the quality, so I would watch out for that if I were you.