Since uploading gifs directly doesn’t seem to work and even if it did its limited to 2mb (makes sense), you need to upload gifs to a separate site and then embed it here.

My website has a gif converter and I just added a button to it which also lets you upload the image to freeimage.host, and gives you the link normally or in markdown

To embed the gif in a post body or in a comment, you use the markdown copy/paste in the text window.

To post a post with a gif, you can just paste the link into the ‘URL’ field.

Hopefully this is helpful or even useful to begin with