public static void AddImageWatermark() { WordFile wordFile = new WordFile(); WordDocument document = wordFile.Import(File.ReadAllBytes("Sample.docx")); WordDocumentBuilder builder = new WordDocumentBuilder(document); //Customize the setting of image watermark ImageWatermarkSettings setting = new ImageWatermarkSettings(); setting.Width = 100; setting.Height = 50; setting.Rotation = -45; using (Stream stream = File.OpenRead("watermark.png")) { setting.ImageSource = new Basic.Media.ImageSource(stream, "png"); } //Create watermark with settings Watermark imageWatermark = new Watermark(setting); //Add watermark to Header object builder.SetWatermark(imageWatermark, document.Sections[0].Headers.Add()); //builder.SetWatermark(imageWatermark, document.Sections[0], HeaderFooterType.Default); File.WriteAllBytes("AddImageWatermark.docx", wordFile.Export(document)); }