As you may have noticed, a new CentOS 6 installation will not have network access by default. You can run the command setup (as you were used to from CentOS 5) but might end up with the response: command not found
What to do now?
You can try to locate setup by typing: which setup
If you are lucky you will find it (often in usr/sbin/setup) but you could also get the response: no setup in....
So the next option is to configure the network settings manually: