The first time that you run the application, it will not have any idea where you are located and will not know which serial port to use for communicating with your mount. Whilst in this mode, the main window will have most of the controls disabled and the LST (local sidereal time) display will not be accurate (unless you happen to be at latitude 0, longitude 0).
The first thing to do is open the Preferences window (Mount -> Preferences...). Then select the Location tab so we can tell the software where you are located.
Next, plug in the serial port that you intend to use with your mount and follow this procedure:
That’s it! You should now be fully configured for use. You should notice that the LST display is now accurate for your location and the Sky Chart should now correctly represent the sky as it appears in your chosen location (although it may take up to 30 seconds to update once you change site).