JavaScript in PDF Fillable Form to auto-populate a field based on ONE choice from radio button list

I'm checking back in. I've worked with what was provided on March 19th. I've still not able to see the function that I need. I'm asking for a bit more instruction as to where this script should be entered (the auto-pop field or radio buttons). Thank you.

Set the export values ("choices" for radio buttons) to the heading text (Student Development, Interagency Collaboration, Student-Focused Planning, Program Structure, Family Involvement) and enter the following calculation script in the heading text field:

this.getField("Radio1").value=="Off"?event.value="":event.value=this.getField("Radio1").value;

Change the name of Radio1 to the actual radio button group field name.

You can't expand pages as the user types with an Acro Form (PDF form created with Adobe Acrobat).