To make a new post, just place the URL for an animated image (GIF, WEBP, WEBM, etc.) into the URL field. Otherwise, in a comment, use the standard image embed syntax like so:

![optional alt text here, or just put nothing within these square brackets](https://feddit.org/pictrs/image/eea34025-5770-4e13-9382-f7399faaeaf1.gif)