First of all, if you have a problem it's best to make a seperate thread for it. Secondly, if you have a problem concerning the Chat then do post in the 'Chat Support' thread. It is stickied on the top for a reason.
And as for your query, make sure you have Java installed when you try accessing the chat, as the applet will only work for you if you have it installed. Or even try downloading a different Client (i.e: mIRC, X-chat, etc...) but I'd recommend the Java applet if you're new to IRC.