Instagram Stories - View and Post
Instagram has a tab called Stories, which is a supplementary feed at the top of the main feed. It includes the users' photo bubbles you track.
To see the user's story or the stories they have written over the last 24 hours, tap a bubble. You might note how close the Instagram Stories functionality is to it if you're familiar with Snapchat.
Tap your photo bubble from the main feed or swipe right on any tab to enter the Stories camera tab in order to post your post.