Then you double-click on the added player-name and you'll be in the ICO lobby.
You'll be able to join all games that are hosted by people set up to host. By that I mean, until patch 1.1 comes out (with NAT-traversal type netcode) you'll need to follow the steps in my guide "Networking and SINS" in order to HOST games. My guide can be found linked-to right under the GREEN writing in the OP of
this thread.
the Monk