Well, it depends on the platform you're using for your story. On most common ones, there's usually a button or option labeled something like 'link' or 'web address'. Then you just paste the URL of the link you want to add.
It's usually quite simple. Just look for an option like 'insert link' or 'add URL' when you're editing your story. It might be in the toolbar or settings.
To post a link on your story, first find the area where you can input text. Then, look for an icon that represents adding a link. Click on it and enter the link's URL. Make sure the link is valid and relevant to your story.