here's how i do it:
step one: get the gif you want off of tenor.com (download the gif too)
step two: open discord and use the bot "esmbot" (if you have it in "my apps" or in a server you're in, preferably "my apps" and inside a private server of yours) and its command "/caption"
step three: enter your wanted caption
step four: upload the gif
step five: (optional) set "togif" to true so you can download it as a gif and not an mp4
step six: press enter and save your captioned gif
then you know how to upload and post gifs so-