The control-panel is a launching pad for a number of different system administration tools which make your life a lot easier by letting you configure things without remembering config file formats and awkward command line options.
To start the control-panel, start X Windows with startx and type control-panel in an xterm. You will need to be root to run the control-panel tools successfully.
Double clicking on the icon for each tool starts it up. Please note that you are not prevented from starting two instances of any tool, but doing so is a very bad idea. 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.