Socket.io & Node.js app - fix up very basic private messaging system

I have a small [login to view URL] and node.js app that is currently just a 'who's online' list of users. It is part of a larger Ruby on Rails site - the Rails app is hosted on heroku and contains the [login to view URL] client code, and the node.js [login to view URL] server is hosted on NodeJitsu. I'm trying to build a very simple function whereby a user can click a button next to another user's name in the list of online users, and it then make a message appear on the target user's screen. I've done my best to build this feature but can't quite get it to work. I'm looking for an expert in [login to view URL] who can come in and fix this easily in a short amount of time. I'm hoping to deploy the entire application into production at the end of this week, so need immediate help.