The Edit Locations window is opened from the Locations window using an individual Location's Edit button and allows you to edit a specific Location:
You may select Spurs, Yards, Classification/Interchange or Staging Only (if greyed out, the option is not available at this Location)
No Staging tracks at this Location.
You may edit another Track at this Location using the Edit button column
for any of the Tracks shown.
You add a new Track by selecting the Track Type and clicking Add [Type] Track
This window is basically the same as the Add Location window.
At the bottom of the Edit Location pane are two more buttons: