using Word = Microsoft.Office.Interop.Word;
private Word.ApplicationClass oWord = new Word.ApplicationClass();            
object savechanges = false;
            object readOnly = false;
            object isVisible = true;
            object missing = System.Reflection.Missing.Value;
            object file = @"C:\Dokumente und Einstellungen\martin\Eigene Dateien\Visual Studio 2005\Code Snippets\Visual C#\My Code Snippets\Word Vorlage laden\Dok1.dot";
            object file1 = @"C:\Dokumente und Einstellungen\martin\Eigene Dateien\Visual Studio 2005\Code Snippets\Visual C#\My Code Snippets\Word Vorlage laden\Dok1.doc";
            object oBookMark = "lol";
            String textMarkerWert = textBox1.Text.ToString();
            Word.Document oWordDoc = oWord.Documents.Open(ref file, 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);

            oWordDoc.Activate();
            oWordDoc.Bookmarks.get_Item(ref oBookMark).Range.Text = textMarkerWert;
            oWord.Selection.TypeParagraph();

            /*oWordDoc.SaveAs(ref file1, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing
                , ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing
                , ref missing, ref missing); 
             * */
            oWordDoc.Close(ref savechanges, ref missing, ref missing);