application page in visual studio

Question

i'm bigginer. i used site https://www.macaw.nl/artikelen/extreme-new-document-button-makeover for creating application page which will open when someone click on button. i create button in ribbon, bu when i click on button, application page is opening with error

 

The method or operation is not implemented.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NotImplementedException: The method or operation is not implemented.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[NotImplementedException: The method or operation is not implemented.]
   NOVODUGME.Layouts.NOVODUGME.TemplateSelector.SetTemplateLibraryFolders() +72
   NOVODUGME.Layouts.NOVODUGME.TemplateSelector.Page_Load(Object sender, EventArgs e) +107
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +42
   System.Web.UI.Control.OnLoad(EventArgs e) +132
   Microsoft.SharePoint.WebControls.UnsecuredLayoutsPageBase.OnLoad(EventArgs e) +101
   Microsoft.SharePoint.WebControls.LayoutsPageBase.OnLoad(EventArgs e) +49
   System.Web.UI.Control.LoadRecursive() +66
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2428

based on this code, method settemplatelibraryfolders() is not implemented.

my aspx application page is

<%@ Assembly Name="$SharePoint.Project.AssemblyFullName$" %>
<%@ Import Namespace="Microsoft.SharePoint.ApplicationPages" %>
<%@ Register Tagprefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
<%@ Register Tagprefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
<%@ Register Tagprefix="asp" Namespace="System.Web.UI" Assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>
<%@ Register TagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"%>
<%@ Import Namespace="Microsoft.SharePoint" %>
<%@ Assembly Name="Microsoft.Web.CommandUI, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TemplateSelector.aspx.cs" Inherits="NOVODUGME.Layouts.NOVODUGME.TemplateSelector" DynamicMasterPageFile="~masterurl/default.master" %>

<asp:Content ID="PageHead" ContentPlaceHolderID="PlaceHolderAdditionalPageHead" runat="server">
<script language='javascript' type="text/javascript">
    // Open template with the corresponding Office app
    function OpenNewTemplate(strTemplate, strSaveLocation) {
        var strProgID = "SharePoint.OpenDocuments";
        createNewDocumentWithProgID(makeAbsUrl(strTemplate),makeAbsUrl(strSaveLocation), strProgID, false);
        window.frameElement.commitPopup();
    }
</script>


</asp:Content>

<asp:Content ID="Main" ContentPlaceHolderID="PlaceHolderMain" runat="server">

<div>
<div id="Navigation" style="position: absolute; top: 0; left: 0; width: 30em">
      <asp:TreeView ID="tvFolders" runat="server"></asp:TreeView>
</div>
<div id="Content" style="margin-left: 30em;">
    <asp:ListView ID="lvTemplates" runat="server" GroupItemCount="5" DataKeyNames="Title">
    <LayoutTemplate>
       <table cellpadding="5" runat="server" id="tblTemplates">
             <tr id="groupplaceholder" runat="server"></tr>
       </table>
    </LayoutTemplate>
   <GroupTemplate>
             <tr id="itemPlaceholderContainer" runat="server" style="height: 80px;">
                 <td id="itemPlaceholder" runat="server"></td>
             </tr>
   </GroupTemplate>
   <ItemTemplate>
        <td id="Td1" valign="top" align="center" style="width: 100px;" runat="server">
           <asp:HyperLink ID="TemplateLink" runat="server" NavigateUrl='<%# Eval("Url") %>' Target="">
             <asp:Image ID="IconImage" runat="server" ImageUrl='<%# Eval("ImageUrl") %>' />
               <br />

                <%# Eval("Title") %>
            </asp:HyperLink>
        </td>
    </ItemTemplate>
    </asp:ListView>
</div>
</div>



</asp:Content>

<asp:Content ID="PageTitle" ContentPlaceHolderID="PlaceHolderPageTitle" runat="server">
Application Page
</asp:Content>

<asp:Content ID="PageTitleInTitleArea" ContentPlaceHolderID="PlaceHolderPageTitleInTitleArea" runat="server" >
My Application Page
</asp:Content>

code cs file is

 

using System;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using Microsoft.SharePoint.Administration;
using System.Collections;
using System.Data;
using Microsoft.SharePoint.Utilities;
using System.Web;


namespace NOVODUGME.Layouts.NOVODUGME
{

    public partial class TemplateSelector : LayoutsPageBase
    {



public readonly DataTable _dataTable = new DataTable();





        protected void Page_Load(object sender, EventArgs e)
        {

            if (!IsPostBack)
                  {
                      // Instantiate the folder tree if first time on page
                         SetTemplateLibraryFolders();
                  }
                      // Add columns to the datatable
                            _dataTable.Columns.Add("ImageUrl", typeof(string));
                            _dataTable.Columns.Add("Title", typeof(string));
                            _dataTable.Columns.Add("Url", typeof(string));
                      // if there's no node selected, select the first node,which is the root.
                         var selectedNode = tvFolders.SelectedNode == null ?tvFolders.Nodes[0].Value :
                         tvFolders.SelectedNode.Value;

                       GetTemplatesInSelectedFolder(selectedNode);

                             // set the templates as the datasource for the template list view
                                lvTemplates.DataSource = _dataTable;


          }

        private void SetTemplateLibraryFolders()
        {
            throw new NotImplementedException();
        }



        private void GetTemplatesInSelectedFolder(string folderUrl)
        {
            using (SPSite site = new SPSite("http://test-net.dri.local"))
                         {
                       using (SPWeb web = site.OpenWeb())
                             {
                                   SPList list = web.Lists.TryGetList("Templates");
                                   if (list != null)
                                      {
                                         SPDocumentLibrary docLib = (SPDocumentLibrary)list;
                                         SPFolder folder = web.GetFolder(folderUrl);
                                         AddFilesToDataTable(web, folder);
                                      }
                             }
                        }
             }



        private void AddFilesToDataTable(SPWeb docWeb, SPFolder folder)
           {
            foreach (SPFile file in folder.Files)
              {
                // get template icon
                string docIcon = SPUtility.ConcatUrls("/_layouts/images/",SPUtility.MapToIcon(file.Web, SPUtility.ConcatUrls(file.Web.Url, file.Url),"",IconSize.Size32));

                // absolute url of the template
                string absUrl =(string)file.Item[SPBuiltInFieldId.EncodedAbsUrl];
                // click action
                string action;
                if (!String.IsNullOrEmpty(HttpContext.Current.Request.QueryString["DocLib"]))
                     {
                    // get the list from the List query string
                          Guid? docLibId = new Guid(HttpContext.Current.Request.QueryString["DocLib"]);
                          SPList selectedLibrary = docWeb.Lists.GetList(docLibId.Value,true);
                          string docLibUrl = selectedLibrary.DefaultViewUrl;
                    // remove Forms[%] from the view url to get the
                    // correct document library url
                          docLibUrl = docLibUrl.Remove(docLibUrl.LastIndexOf("Forms",StringComparison.Ordinal));
                action = string.Format("javascript:OpenNewTemplate('{0}', '{1}');",absUrl,SPContext.Current.Site.RootWeb.Url + docLibUrl);
                AddDataToDataTable(docIcon, file.Name, action);
                }


               }
           }


              private void AddDataToDataTable(string docIcon,string title,string url)
                 {
                     DataRow row = _dataTable.NewRow();
                     row["ImageUrl"] = docIcon;
                     row["Title"] = title;
                     row["Url"] = url;
                     _dataTable.Rows.Add(row);
                 }




    }



}

where is error? can someone help me with some guide