I want to add my own gif instead of this preloader
You can extend/override the LoadingIndicator component https://api.docs.flarum.org/js/v0.1.0-beta.15/class/src/common/components/loadingindicator.js~loadingindicator
I see you tried attaching an image from Gmail.
While you might be able to see the image yourself, nobody else can see the image.
You can use a free image hosting website like Imgur to attach images on this forum.
