If by the drop-down menus you mean spoilers, you use [spoiler].
[spoiler=Title]Content[/spoiler]
Content
[spoiler= ]Thin spoiler[/spoiler]
Thin spoiler
I don't know what GIFs you're referring to, but they'll be embedded like any old image, hosted on Imgur, Discord or Tumblr, probably. Either use the image UI and uncheck "Retrieve remote file and reference locally" or use BBCode directly.