line attractor on surface help

Hi there

This is the first GH DEFINITION I TRIED TO FOLLOW THROUGH DIGITAL TOOLBOX ON YOUTUBE(CURVE AND POINT ATTRACTOR ON SURFACE) . SOMETHING  WENT WRONG . PLEASE HELP WITH THE DEFINITION.

I ALSO HAVE SOME QUERRIES
1) WHAT IS THE VALUE OF FX2 AND FX1 . ITS OVERALL RELATION WITH DEFN ?
2)WHEN I EXPORT HIGH RESOLUTION IMAGE OF THE FILE IT SPLITS INTO PARTS AND OUTPUTS 2-3-4- PNG FILES INSTEAD OF ONE.HOW CAN IT BE FIXED ?

NOTE : PLEASE EXPLAIN THE BUTTONS IN PANELS IN EXAMPLE FILES , ITS(BUTTON) OVERALL RELATION IN THE DEFINITION .
THE RHINO FILE UNITS ARE IN METERS
the ghx file with . the image is attached