To add it to a post or page, click the black plus sign and type in “little image” in the search field. To edit the block, see the settings in the right-hand sidebar. If you need more space, click the pencil icon on the block to switch to Edit Mode. While in Edit Mode, the settings move from the sidebar to the Block Editor. Click the eye icon to switch it back.
With this block, you can also add a video instead of an image. To add a video, simply copy/paste a YouTube or Vimeo link in the video field.