// Create an instance of an HTML document
using (var document = new HTMLDocument())
{
    var body = document.Body;

    // Create a paragraph element
    var p = (HTMLParagraphElement)document.CreateElement("p");

    // Set a custom attribute
    p.SetAttribute("id", "my-paragraph");

    // Create a text node
    var text = document.CreateTextNode("my first paragraph");

    // Attach the text to the paragraph
    p.AppendChild(text);

    // Attach the paragraph to the document body
    body.AppendChild(p);

    // Save the HTML document to a file
    document.Save(Path.Combine(OutputDir, "edit-document-tree.html"));
}