The sample demonstrates how to merge two documents.

private void button1_Click(object sender, EventArgs e)
{
    string fileName = OpenFile();
    string fileMerge = OpenFile();
    if ((!string.IsNullOrEmpty(fileName)) && (!string.IsNullOrEmpty(fileMerge)))
    {
        //Create word document
        Document document = new Document();
        document.LoadFromFile(fileName,FileFormat.Doc);

        Document documentMerge = new Document();
        documentMerge.LoadFromFile(fileMerge, FileFormat.Doc);

        foreach( Section sec in documentMerge.Sections)
        {
            document.Sections.Add(sec.Clone());
        }

        //Save doc file.
        document.SaveToFile("Sample.doc", FileFormat.Doc);

        //Launching the MS Word file.
        WordDocViewer("Sample.doc");
    }


}

private string OpenFile()
{
    openFileDialog1.Filter = "Word Document (*.doc)|*.doc";
    openFileDialog1.Title = "Choose a document to merage";

    openFileDialog1.RestoreDirectory = true;
    if (openFileDialog1.ShowDialog() == DialogResult.OK)
    {
        return openFileDialog1.FileName;
    }

    return string.Empty;
}

private void WordDocViewer(string fileName)
{
    try
    {
        System.Diagnostics.Process.Start(fileName);
    }
    catch { }
}

Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles button1.Click
	Dim fileName As String = OpenFile()
	Dim fileMerge As String = OpenFile()
	If ((Not String.IsNullOrEmpty(fileName))) AndAlso ((Not String.IsNullOrEmpty(fileMerge))) Then
		'Create word document
		Dim document_Renamed As New Document()
		document_Renamed.LoadFromFile(fileName,FileFormat.Doc)

		Dim documentMerge As New Document()
		documentMerge.LoadFromFile(fileMerge, FileFormat.Doc)

		For Each sec As Section In documentMerge.Sections
			document_Renamed.Sections.Add(sec.Clone())
		Next sec

		'Save doc file.
		document_Renamed.SaveToFile("Sample.doc", FileFormat.Doc)

		'Launching the MS Word file.
		WordDocViewer("Sample.doc")
	End If


End Sub

Private Function OpenFile() As String
	openFileDialog1.Filter = "Word Document (*.doc)|*.doc"
	openFileDialog1.Title = "Choose a document to merage"

	openFileDialog1.RestoreDirectory = True
	If openFileDialog1.ShowDialog() = DialogResult.OK Then
		Return openFileDialog1.FileName
	End If

	Return String.Empty
End Function

Private Sub WordDocViewer(ByVal fileName As String)
	Try
		Process.Start(fileName)
	Catch
	End Try
End Sub