public void SetAll( 
   float left,
   float right,
   float top,
   float bottom,
   float header,
   float footer
)

public static void PageMarginsAndPageBreaks()
{
  using( var workbook = Workbook.Create( PageLayoutSample.PageLayoutSampleOutputDirectory + @"PageMarginsAndBreaks.xlsx" ))
    {
      // Gets the first worksheet; a workbook always contains at least 1 worksheet.
      var worksheet = workbook.Worksheets[0];
	  
      // Adds a title.
      worksheet.Cells["B1"].Value = "Page Margins and Breaks";
      worksheet.Cells["B1"].Style.Font = new Font() {Bold = true, Size = 15.5d};
	  
      // Sets all margins using custom values
      worksheet.PageLayout.Margins.SetAll( 0.7f, 0.7f, 0.5f, 0.5f, 0.4f, 0.4f );

      // Saves workbook to disk.
      workbook.Save();
      Console.WriteLine( "/tCreated:PageMarginsAndBreaks.xlsx/n" );
    }
}