// First level

        tm1.Add(null, "id_brands", "Brands", "javascript:alert('you clicked me');void(0);", null);
        tm1.Add(null, "id_systems", "Systems", null, null);

                // Sub menu

                tm1.Add("id_brands", "id_ibm", "IBM", null, null);
                tm1.Add("id_brands", "id_obout", "OBOUT", "http://www.obout.com/", null);
        
                        // Sub menu
        
                        tm1.Add("id_obout", "id_tree", "Treeview", "treeview.aspx", null);
                        tm1.Add("id_obout", "id_calendar", "Calendar", "calendar.aspx", null);

<tm:TextMenu runat="server" id="TextMenu1">
         
                // First level
                <tm:Item ID="brands" InnerHtml="Brands" Url="javascript:alert('you clicked me');void(0);"></tm:Item>
                <tm:Item ID="systems" InnerHtml="Systems"></tm:Item>
                         
                        // Sub menu
                        <tm:Item ParentID="brands" ID="ibm" InnerHtml="IBM"></tm:Item>
                        <tm:Item ParentID="brands" ID="obout" InnerHtml="OBOUT" Url="http://www.obout.com/"></tm:Item>
                         
                                // Sub menu
                                <tm:Item ParentID="obout" ID="treeview" InnerHtml="TreeView" Url="treeview.aspx"></tm:Item>
                                <tm:Item ParentID="obout" ID="calendar" InnerHtml="Calendar" Url="calendar.asp"></tm:Item>
...
</tm:TextMenu>