Create word document using Open XML SDK in C#.net

word-doc.cs

public static StyleDefinitionsPart AddStylesPartToPackage2(WordprocessingDocument doc)
        {
            StyleDefinitionsPart part;
            part = doc.MainDocumentPart.AddNewPart<StyleDefinitionsPart>();
            Styles root = new Styles();
            root.Save(part);
            return part;
        }

        // Create a new style with the specified styleid and stylename and add it to the specified
        // style definitions part.
        private static void AddNewStyle(StyleDefinitionsPart styleDefinitionsPart,
            string styleid, string stylename)
        {
            // Get access to the root element of the styles part.
            Styles styles = styleDefinitionsPart.Styles;

            // Create a new paragraph style and specify some of the properties.
            Style style = new Style()
            {
                Type = StyleValues.Paragraph,
                StyleId = styleid,
                CustomStyle = true
            };
            StyleName styleName1 = new StyleName() { Val = stylename };
            BasedOn basedOn1 = new BasedOn() { Val = "Normal" };
            NextParagraphStyle nextParagraphStyle1 = new NextParagraphStyle() { Val = "Normal" };
            style.Append(styleName1);
            style.Append(basedOn1);
            style.Append(nextParagraphStyle1);

            // Create the StyleRunProperties object and specify some of the run properties.
            StyleRunProperties styleRunProperties1 = new StyleRunProperties();
            DocumentFormat.OpenXml.Wordprocessing.Bold bold1 = new DocumentFormat.OpenXml.Wordprocessing.Bold();
            DocumentFormat.OpenXml.Wordprocessing.Color color1 = new  DocumentFormat.OpenXml.Wordprocessing.Color { ThemeColor = ThemeColorValues.Accent2 };
            RunFonts font1 = new RunFonts() { Ascii = "Lucida Console" };
            Italic italic1 = new Italic();
            // Specify a 12 point size.
            FontSize fontSize1 = new FontSize() { Val = "24" };
            styleRunProperties1.Append(bold1);
            styleRunProperties1.Append(color1);
            styleRunProperties1.Append(font1);
            styleRunProperties1.Append(fontSize1);
            styleRunProperties1.Append(italic1);

            // Add the run properties to the style.
            style.Append(styleRunProperties1);

            // Add the style to the styles part.
            styles.Append(style);
        }

        // Return true if the style id is in the document, false otherwise.
        public static bool IsStyleIdInDocument(WordprocessingDocument doc,
            string styleid)
        {
            // Get access to the Styles element for this document.
            Styles s = doc.MainDocumentPart.StyleDefinitionsPart.Styles;

            // Check that there are styles and how many.
            int n = s.Elements<Style>().Count();
            if (n == 0)
                return false;

            // Look for a match on styleid.
            Style style = s.Elements<Style>()
                .Where(st => (st.StyleId == styleid) && (st.Type == StyleValues.Paragraph))
                .FirstOrDefault();
            if (style == null)
                return false;

            return true;
        }

        // Apply a style to a paragraph.
        public static void ApplyStyleToParagraph(WordprocessingDocument doc,
            string styleid, string stylename, Paragraph p)
        {
            // If the paragraph has no ParagraphProperties object, create one.
            if (p.Elements<ParagraphProperties>().Count() == 0)
            {
                p.PrependChild<ParagraphProperties>(new ParagraphProperties());
            }

            // Get the paragraph properties element of the paragraph.
            ParagraphProperties pPr = p.Elements<ParagraphProperties>().First();

            // Get the Styles part for this document.
            StyleDefinitionsPart part =
                doc.MainDocumentPart.StyleDefinitionsPart;

            // If the Styles part does not exist, add it and then add the style.
            if (part == null)
            {
                part = AddStylesPartToPackage(doc);
                AddNewStyle(part, styleid, stylename);
            }
            else
            {
                // If the style is not in the document, add it.
                if (IsStyleIdInDocument(doc, styleid) != true)
                {
                    // No match on styleid, so let's try style name.
                    string styleidFromName = GetStyleIdFromStyleName(doc, stylename);
                    if (styleidFromName == null)
                    {
                        AddNewStyle(part, styleid, stylename);
                    }
                    else
                        styleid = styleidFromName;
                }
            }

            // Set the style of the paragraph.
            pPr.ParagraphStyleId = new ParagraphStyleId() { Val = styleid };
        }
        public static string GetStyleIdFromStyleName(WordprocessingDocument doc, string styleName)
        {
            StyleDefinitionsPart stylePart = doc.MainDocumentPart.StyleDefinitionsPart;
            string styleId = stylePart.Styles.Descendants<StyleName>()
                .Where(s => s.Val.Value.Equals(styleName) &&
                    (((Style)s.Parent).Type == StyleValues.Paragraph))
                .Select(n => ((Style)n.Parent).StyleId).FirstOrDefault();
            return styleId;
        }
        private void button_word2(object sender, EventArgs e)
        {
            try
            {
                using (WordprocessingDocument doc = WordprocessingDocument.Create("test11.docx", DocumentFormat.OpenXml.WordprocessingDocumentType.Document))
                {
                    // Add a main document part.
                    MainDocumentPart mainPart = doc.AddMainDocumentPart();


                    var styleid = "ddd";
                    var stylename = "xx";



                    // Create the document structure and add some text.
                    mainPart.Document = new DocumentFormat.OpenXml.Wordprocessing.Document();
                    Body body = mainPart.Document.AppendChild(new Body());
                    DocumentFormat.OpenXml.Wordprocessing.Paragraph para = new Paragraph();
                    Run run = new Run();
                    Text text = new Text("Some text");
                    run.Append(text);
                    para.Append(run);
                    body.InsertAt<Paragraph>(para, 0);

                    Paragraph p = mainPart.Document.Body.Descendants<Paragraph>().ElementAtOrDefault(0);
                    // Check for a null reference. 
                    if (p == null)
                    {
                        throw new ArgumentOutOfRangeException("p","Paragraph was not found.");
                    }


                    ApplyStyleToParagraph(doc, "OverdueAmount", "Overdue Amount", p);
                }
            }

            catch (Exception)
            {

                throw;
            }
        }
    }