XML paragraph code to an existing word docx file using open xml sdk 2.0

How to add a XML paragraph code to an existing word docx file using open xml sdk 2.0 in .net

<w:p xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">
    <w:pPr>
        <w:jc w:val="left" />
    </w:pPr>
    <w:r>
        <w:rPr>
            <w:color w:val="auto" />
            <w:b />
            <w:rFonts w:ascii="Arial" w:hAnsi="Arial" w:cs="Arial" />
            <w:sz w:val="28" />
        </w:rPr>
        <w:t>Hello World</w:t>
    </w:r>
</w:p>

can it be done using AddCustomXmlPart or AddNewPart<CustomXmlPart>()

Regards

This code should do what you're wanting:

/// <summary>
/// Add a paragraph with the given <param name="text"/> to the <param name="docName"/>
/// </summary>
/// <param name="docName">Name of the document.</param>
/// <param name="text">The text to insert into the document.</param>
public static void AddParagraphWordprocessingDocumentWithText(string docName, string text)
{
    // Open the Wordprocessing document.
    using (WordprocessingDocument wordprocessingDocument = WordprocessingDocument.Open(docName, true))
    {
        Text docText = new Text(text);

        Run run = new Run(docText);

        Paragraph paragraph = new Paragraph(run);

        wordprocessingDocument.MainDocumentPart.Document.Body.Append(paragraph);

        // Save changes to the main document part.
        wordprocessingDocument.MainDocumentPart.Document.Save();
    }
}