Re: When the user of my form clicks a box/radio button, a predefined text will appear elsewhere in the form. How do I do this?

Have this as the mouse up script for the checkbox:

if (event.target.value!="Off") {  //If checkbox is ticked
this.getField("Textbox1").value = "Instructions for Neck Pain Go Here";  //Replace Textbox1 with the name of your field
}
else this.getField("Textbox1").value = "";   //Clear the text field if checkbox is not ticked