[CentOS] CentOS: Install Packages Via yum Command Using DVD / CD as Repo

I'm confused about this.  Is this supposed to work without me mounting my CD/DVD?  If you are supposed to mount it, what path should you use to make this work?

   http://www.cyberciti.biz/faq/centos-linux-install-packages-from-dvd-using-yum/

 === Al