@‘s are mentions for getting specific users (or a group) attention. to share a topic, simply click the time stamp that is top right corner of a post to bring up the copy/ share modal, or the link icon below the post. then you can send the link to whoever you like. To share a whole topic, click the share button at the topic footer:
click the blue copy square and it will turn green to show it’s been copied
note that Meta has this theme component installed, so the link at the bottom here is an immediate copy to clipboard, but default without the component will pop up the share modal.