Right, to play online heres how you go about it.
When you turn ESF on, click on multiplayer game and then choose internet games. You will be able to find all servers here (be sure to set your filter so that it will find ESF servers)
An alternate is to download a programme called
The All Seeing Eye which is a programme that will find servers for all sort of games, including ESF (this is what i use)
Be sure to have the latest version of halflife (
1.1.1.0) to be able to play online.