static void Main(string[] args)
{
var wordBytes = File.ReadAllBytes("Sample.docx");
var image = new Bitmap("Sample.png");
using (MemoryStream imageStream = new MemoryStream(image.ToByteArray()))
using (MemoryStream docStream = new MemoryStream())
{
docStream.Write(wordBytes, 0, wordBytes.Length);
using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(docStream, true))
{
MainDocumentPart mainPart = wordDoc.MainDocumentPart;
ImagePart imagePart = mainPart.AddImagePart(imageStream);
var imageElement = mainPart.CreateElement(imagePart, "Image", image.GetWidthInEMUs() / 3, image.GetHeightInEMUs() / 3, "right", 0, 0, 0);
wordDoc.MainDocumentPart.Document.Body.InsertAt(new Paragraph(new Run(imageElement)), 0);
}
wordBytes = docStream.ToArray();
}
File.WriteAllBytes("Result.docx", wordBytes);
}