You don't need to calculate these values. You need to use them in order to define the dimensions and location of the wire. X1, Y1, and Z1 defines the X, Y, and Z coordinate locations of one end of the wire while X2, Y2, and Z2 defines the X, Y, and Z coordinate locations of the other end of the wire. Also, the Radius define the radius of the wire in meters:

In my example, the wire has 50 meters length and its radius has 0.0001 meters:

I recommend you check the official tutorials (below Information section) for further details. Also, you can contact the developers using 4nec2@gmx.net
email address.