How do I update the IcedTea Plugin on 12.10?
First, Ubuntu 12.10 is not supported anymore. Update to 13.10 or "downgrade" to 12.04 LTS.
Secondly, the Icedtea plugin can be installed by running the following command in terminal: "sudo apt-get install icedtea-7-plugin"
After that just enter your password and press "Y" for yes to install.