If you take this code that is on another site and paste it in you "Edit Html" page then you can have the embed code box.
I made two animated gifs below. Uploaded them to a site that allows animated gifs. There it gave me an embed code. I did like the other site said and look it works. =o)
The Baltimore Oriole below is a .gif file that I made. The background is transparent so it will work on everyone's sites.