Below is the Midi Port setup screen.

It shows the midi In and Out ports that are currently available and the ports you have previously selected (shown in orange highlight). Before bringing up the screen you should have all your instruments turned on and connected to the computer. Click on any port to select or delete it into/from the active group.

You will select one of the Outputs as your main instrument. Then select it or another as the Drum Instrument.

The Timing Calibration box should be checked when you first install Spanner on a new computer. It will cause a few seconds delay at start-up while it runs some performance tests on your system and makes adjustments. You can see the results in the Main Log (it's on the Main Help screen).