The Red Hat control-panel is a gui interface, running under X, that allows easy administration of a Red Hat Linux System. Most of the configuration parameters can be adjusted using the control-panel. control-panel has to be run by the super-user, root. If you are running as a regular user, as recommended, you can use the su command in a xterm, to become root, then start control-panel from that xterm. If you just call control-panel you may get an error like this.
$ su -
** WARNING **: cannot open display:
To activate the control-panel from an xterm, where you su to root,
take the following stepst.
$ su -
# export DISPLAY=0:0