Trying to enable calendar publishing in Exchange 2010

Hello,

I am trying to enable internet calendar publishing as per an article I found on technet.

The second step in the configuration process wants me to use the shell to enable the publishing virtual directory.

The example syntax is: 

Set-OwaVirtualDirectory -Identity "CAS01" -ExternalUrl "<URL for the CAS01>"
I need a little help filling in the blanks.  My internal exchange server name is "adas2010-2", my web url is "mail.adasisrael.org/exchange"
No matter what I put in place of "CAS01" I get an error telling me that it can't be found on my DC.
What would be the proper syntax for this command?
Thanks, Jack