Last week, Facebook users around the world were greeted with a mysterious change. There, atop the usual news feed, was a row of circles. Inside each circle, a photo of one of their friends.hoWhat in the world is happening , cried out millions of people over 30 who have never used Snapchat. It's a new Facebook feature called Stories, and it's an imitation of a popular feature on rival app Snapchat ( SNAP ). Facebook previously added Stories to Instagram, but this latest roll out on its core iOS and Android apps reaches far more people. Many of whom are, understandably, confused. We turned to some of CNNTech's resident millennials and Facebook ( FB , Tech30) itself for tips on how to use Stories without embarrassing yourself. What is a Story? A Story is a collection of videos and photos from the past day. It is separate from the photos and videos you share in your newsfeed. You start with one item -- say, a shot of a good dog you met on the way to wo...