to the best of my knowledge, Kubuntu (all the debian derivatives) don't use rpm's (RPM=redhat package manager). Debian derivatives use .deb files - normally available from (probably) some sort of package manager.
I'm guessing, but there should be some sort of package manager application somewhere in there - which should (if what I've read is correct) point your system at a mirror/repository for the correct packages for the distro this link
looks like it's telling you how that should be done. Ha! though it also points you towards the main "quick guide" for it as well.
Hope that helps some.