The chat will take a moment to load...
Once the applet is loaded, then you will be able to enter in a username. Please be aware that the username you use on the board might well not be available on IRC. If a message appears informing you that the nickname you are using you need to type: /nick yournewnick.
If you have a client like mIRC, you will be able to log into the chatroom direct at irc.webchat.org on port 6667, room #spaced.