In this clip, you'll learn how to retweet or RT someone else's post on Twitter and share it with your followers. What do President Obama, the Dalai Lama and Justin Bieber have in common? Why, they're all on Twitter, of course. Join the party. Whether you're new to Twitter's popular microblogging application or just missed a few of the essentials along the way, you're sure to benefit from this free video tutorial.