/// <summary>
/// Insert field into the first paragraph of the current document using field code and field String.
/// </summary>
private static void InsertFieldUsingFieldCodeFieldString(Document doc, string fieldCode, string fieldValue,
Node refNode, bool isAfter, int paraIndex)
{
Paragraph para = DocumentHelper.GetParagraph(doc, paraIndex);
para.InsertField(fieldCode, fieldValue, refNode, isAfter);
}