How to Microblog in SharePoint 2013
To use the tagging functionality of SharePoint 2013, begin typing your message.
Type in the Newsfeed section of your main page.
To tag a user, enter the @ symbol and the name of the user.
Be sure not to include a space after the @ symbol.
To tag a topic, enter the hashtag (#) symbol and the topic with no space after the # or between words in the topic.
In this example, the hashtag is #SharePoint2013.
Click the Post button.
Your message is posted.
Find your message.
After you post your message, it appears in a number of places: on the site, on anyone’s feed that is following you, and on anyone’s feed that is following the topic you referenced.