You upload the image like you would for a regular post, except instead of actually posting it, you click on the link directly below the image. Doing this will take you to the image’s asset page, where you can get the asset ID. Then just type in the comments “* !asset #[ID HERE]” to embed a thumbnail that links to the asset page. The exclamation point will make it show as an embedded image and the asterisk will make sure the thumbnail in embedded instead of the full image.
