To showcase content from other sources like Instagram, Soundcloud, Slideshare, Quora, Yelp, Google Maps, YouTube, Twitter, Vimeo, and many more, you can use the Embed function.
When inserting content on your post - it is the second icon from the Right, as shown below.
When you click on the embed button, you'll be asked to provide the URL for the page that you would like to embed. Use the page URL, not the "embed code". The media object will then be magically inserted into your post.
If you wrote the original content on another platform, then you should use the Canonical Link. Canonical links help search engines consolidate the information they have for the individual URLs into a single, authoritative URL. Therefore, if you syndicate your content for publication on other domains, canonical links help to consolidate the page ranking to your preferred URL.
Please note that canonical links should only be applied if you actually own the original content. If you are copying someone else's work, you should not apply a canonical link. (Members who do this are in violation of the AUP.)
You enter the Canonical Link in the New Post Window, on the Right Side.