Welcome to the CentOS fora. Please see the recommended reading for new users linked in my signature.
I've just installed CentOS 6.2 and I selected minimal installation. ...
No argument with the advice you have been given, but if you really want a GUI environment it would probably be easier to just chalk the minimal install up to a learning experience and re-install a Desktop system, and pick other desired groups/packages while you are at it.
Even experienced users may have difficulties bootstraping up from a minimal install to a usable GUI system with networking.