Action Details
Requirements and how-to articles for Instagram's action:

Requirements
You need this to get it done:

Video
Video to be posted (up to 15 seconds long.) Either uploaded from the phone's library/gallery or taken in the moment (swipe up to choose one from your gallery.)
iOS, Android or Windows Mobile Device
In order to create a story post, you need to do so using a mobile device via the official Instagram app.
Photo
Photo to be posted. Either uploaded from the phone's library/gallery or taken in the moment (swipe up to choose one from your gallery.)
Draw, Text or Sticker (optional)
You can add drawings, text and/or stickers to the uploaded photo/video.
Story Highlights (optional)
Highlights allow you to curate a collection of story posts to remain on your profile even after they are no longer visible on your story (after the initial 24 hours.) Each highlight can contain up to 100 story posts, and can have its own custom title and thumbnail.
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

0
Instagram Help Centre - Stories
Instagram's official help section offering a guide and FAQ around Instagram stories.
Official
Link missing here or found errors? Improve How-Tos