[CentOS] Setting up YUM or APT

I am using Cent oS 4 and I would like to setup the YUM repositories.
Can anybody help me setup YUM?
THat would be to install software, add repositories, and such necessary stuff.


I know how to use apt-get, but not on Cent OS ( I will use either YUM
or APT, at a time, but learn both of them, sooner or later.)


Thank you.
-- 
"No-one dies a virgin. Life screws everyone."