Instagram Story Publishing

First, open up the compose tab as you normally would when creating a post and select your Instagram account from the drop-down list:

In the bottom-right corner of the text area of the compose tab, you should see your current character count along with the options to add media. Click on the Story option:

On the window that appears, upload your image or video in the same way you normally would attach media to your post, from whichever source you have available:

Once uploaded, your Story media should appear to the right of the Compose Tab:

Thats it! Once you're happy with your Story, either schedule it for the future or publish it straight away and it should look something like this: