private Word.ApplicationClass WordApp = new Word.ApplicationClass();
    protected void Button1_Click(object sender, EventArgs e)
    {
        Installation.doc";
        object fileName = Server.MapPath("/WordSample/WordFiles/Test.doc");
        object readOnly = false;
        object isVisible = true;
 
        object missing = System.Reflection.Missing.Value;
 
        WordApp.Visible = true;
 
        Word.Document aDoc = WordApp.Documents.Open(ref fileName, ref missing, 
 
ref readOnly, ref missing, ref missing, ref missing, ref missing, ref missing, 
 
ref missing, ref missing, ref missing, ref isVisible,ref missing,ref 
 
missing,ref missing,ref missing);
 
        aDoc.Activate();
 
        WordApp.Selection.TypeText("Copyright C# Corner");
        WordApp.Selection.TypeParagraph();
    }