The DscServer is running when the upper widget in this picture is on one of your home screens. The top indicator shows green if the DscServer is connected to your envisalink card, red if not. Touch the widget to open up the client management app. The connection status and information about any error will be shown there, use menu to change the DscServer settings.
The middle widget is the DscKeypad widget. It's not required but is handy to see the status of the DSC alarm system. You would configure this to connect to the local DscServer.
The bottom widget is the DscPartition widget, handy on your carry phone to manage (arm, disarm) your alarm quickly.
You can also create DscCommand widgets on your phone. These are custom DSC commands (like custom keys) that are sent via the DscKeypad app when you touch them, and can be used by automation apps like Tasker or Automagic.