Appreciate your interest in using this feature. If your channel is eligible, you can create Stories with these steps included in our Help Center article: https://goo.gl/zz5SM5 . Hope this helps.
To be able to add video links to your stories, you will first have to create a story using the steps mentioned in the article shared earlier. Later, click on edit story and from there you would see an option to add video links to your story. Hope this helps clarify.