You will need to click on an a pink button after the web page appears in your browser, like this one:
I have tested these applets with sun-java6 on Ubuntu 10.04. I also did this command:
sudo update-alternatives --config javaand selected "2", for sun-java.
But, as always with Java applets, you may need to wait a bit to retrieve the applet across the internet, and for your computer to load it.