When you're on your home feed, you see posts and stories from people you follow. To discover new Instagram content, tap on the search icon in the footer menu.
On the discover page, you see featured posts and stories that are personalised for you based on your usage of Instagram.
Each time you refresh this page, you see new posts & stories.
When you tap on a post, you see the expanded version of it. If it's a video it will autoplay without sound. You can scroll down to see more featured posts.
To watch a story, you tap on one of the circle thumbnails in the header. You can watch the next featured story by swiping from right to left. To close a story, you swipe from the top to the bottom.