thats easy, Home is the home folder... just click the house on the toolbar then make the hidden files visible by clicking "view" show hidden files..... then go to the folder they say(HOME/.mplayer/mplayerplug-in.conf) open the config file and add the code they say and save... give it a try :)
Okay....I'll give it a try when I get home. You can do this using the Live CD, right?