• While composing a text block for a post or comment, you can quickly tag a user by using the at sign (@). 
• As soon as you type the at sign, the editor will display a pick list of users in the course for you to select from.  (The list will filter based on additional text typed immediately after the at sign.) 
• Once you select a user from the list they will be auto-tagged to the post and receive a notification once you publish.