@username of the person you want to talk to (the spaces and - and _ matter so make sure you get them right!!) and then you add a semicolon after ;

you can still ping someone if there is a space between their username and the semicolon (or at least your friends list) but a link just won't appear

@miro
hello! :D
tell me what you did for the holiays man! did you get a computer?