The control panel is a launching pad for a number of different system administration tools. They make your life easier by letting you configure things without remembering configuration file formats and awkward command line options.
To start the control-panel, start the X Window System as root with startx and type control-panel in an xterm. You will need to be root to run the control-panel tools successfully. You can do this as well if you already have X running as a normal user. Just type su -c control-panel and then type the root password when prompted. If you plan to do other tasks as root, you could type su - followed by the root password when prompted. You will then be given a root shell. Here, you will need to type DISPLAY=:0 control-panel & to get the control panel to work. The ``DISPLAY'' part tells the control panel to use your display. This syntax works only for a Bourne-compatible shell like bash. If you run tcsh, you would enter setenv DISPLAY :0; control-panel &.
Double clicking on an icon starts up a tool. Please note that you are not prevented from starting two instances of any tool, but doing so is a very bad idea because you may try to edit the same files in two places and end up overwriting your own changes. If you do accidentally start a second copy of a tool, you should quit it immediately. Also, do not manually edit any files managed by the control-panel tools while the tools are running. Similarly, do not run any other programs that may change those files while the tools are running.