SpreadsheetWatermarkHeaderFooterOptions

public sealed class SpreadsheetWatermarkHeaderFooterOptions : SpreadsheetWatermarkOptions

SpreadsheetLoadOptions loadOptions = new SpreadsheetLoadOptions();
using (Watermarker watermarker = new Watermarker(@"D:\test.xls", loadOptions))
{
    TextWatermark watermark = new TextWatermark("Test", new Font("Arial", 14));

    SpreadsheetWatermarkHeaderFooterOptions options = new SpreadsheetWatermarkHeaderFooterOptions();
    options.WorksheetIndex = 0;

    watermarker.Add(watermark, options);
    watermarker.Save();
}