Tracking Subdomains

I'm a little confused with this plugin.

I would like to track subdomains and I read the KB article at google here.

http://www.google.com/support/googleanalytics/bin/answer.py?hl=en&answer=55524

I'm not really sure where to edit that code though because all I did was put my tracking code into the plugin in the admin panel.

Also I am checking out the source code of all the other blogs on my site but I don't see any tracking code in there. How would google know to track these if there is no tracking code on the page? Are there configuration options somewhere in the site admin panel that I am not seeing?