I've never used yum to pull from the install DVD - search elsewhere for that, but once that's solved use
yum groupinstall "KDE (K Desktop Environment)"
to pull in the KDE packages.
If you can't get yum to work, you can always brute force it.
rpm -ivh kdebase*
check for dependencies and keep adding packages to the line above till it is happy with all dependencies and installs. Look at anything starting with kde, but also kdm if you want the KDE login screen, arts, akonadi, phonon, and I'm sure a few I'm forgetting.
A rpm -ivh kde* will probably get you more packages than you want (the devel packages for example) but will solve most dependencies for you without a hunt and peck.
You should be aware, however, that the KDE version on the DVD was 4.0. It was not yet ready for prime time. They are now shipping 4.2.2 via updates and still don't have 100% of the bugs squashed, particularly with kmail/imap. So if you're going to install KDE do yourself a favor and pull down the updates to install from.