Query on yum install

[Nithya Chandrakesan]

Hi,

I am trying to do yum install of some packages.
But it pops up the error - "Your system is not registered with RHN"

Do I need to register with RHN to do the yum installs? How do I update my
system?
Where do I find the installation numbers for the CDs?

Please advise.

Thanks,
Nithya.