title: how to tag users in application post of a facebook application
body: <p>can anyone please tell me how to tag user's friend in a wall post made by my app on user's wall. 
  say bob is a friend of emily. 
  i have an application that, tells all the friends name starting with e. now when i make a post on bob's wall :
  "hey bob emily i your friend whose name starts with e"
  i want emily to be tagged.</p>
  
  <p>Please let me know how to do it.</p>
  
  <p>thanks!!</p>