The broken picture in the browser is because you don't have Java installed or enabled correctly.
But since you've gone and downloaded mIRC, you might as well use that instead, since that's better than using the java chat, in which case just do what Samuraid mentioned above :p If it still doesn't connect (it can take over a minute if you have a firewall so be patient), copy/paste what you see in the status window and post it here (you copy stuff in mIRC by highlighting it - it'll copy automatically for you).