(( you'll need to upload your desired banner and pfp to a file hosting site like filegarden, imgchest, squidge images, etc. then, right click/long press -> copy image link/copy image url, then paste it into the banner or pfp text box. make sure the link you use has the file extension in it (example: https://blah.com/image.png) otherwise it won't embed correctly. gifs should work for both. see: @arenaceousAlchemy as an example for a gif banner
make sure you DONT us discord for hosting images, as discord image links expire after 24-48 hours. i would also advise against using imgur as it's blocked in the UK, so any users who are from the UK would not be able to see your pfp or banner if you use imgur for a host