I used ! [] (link)

It works tho

@Eggplant You need the .filetype

Ok thank you very much :)

@RailfanEthan do you keep or discard file type? (Link.jpg) or (link.filetype.jpg) ?

-You gotta upload an image to a website (i use imgur, it doesn't require a account)
-Copy the link
-There's a special format you need to use to make it work. In the text of a forum or airplane, you gotta type this out:
! [dead text] (link.filetype).
Remove spaces
The dead text is text that won't appear, and is hidden "behind" the image. The link.filetype is the link of the image, followed by the filetype. .jpg for images, and .gif for animated images.