How Do I Display Names from a ListBox onto a TextBox?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.IO;

namespace DogAdoption_Form
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        const string DISPLAY_NAME = "Name will display here...";

        public MainWindow()
        {
            InitializeComponent();

            //DisplayLstBoxDogNames();
        }

        public void DisplayLstBoxDogNames()
        {
            lstBoxDogNames.Items.Add("Chloe");
            lstBoxDogNames.Items.Add("Daisy");
            lstBoxDogNames.Items.Add("Emmett");
            lstBoxDogNames.Items.Add("Jack");
            lstBoxDogNames.Items.Add("Lucy");
            lstBoxDogNames.Items.Add("Nala");
            lstBoxDogNames.Items.Add("Peach");
            lstBoxDogNames.Items.Add("Rocky");
            lstBoxDogNames.Items.Add("Shiloh");
            lstBoxDogNames.Items.Add("Toby");

            foreach (string dogName in lstBoxDogNames.Items)
            {
                if (txtBoxName.Text == DISPLAY_NAME)
                {
                    //txtBoxName.Text.Replace(DISPLAY_NAME, dogName);
                    txtBoxName.Text = dogName;
                    txtBoxName.Foreground = Brushes.Black;
                }

                else if ((txtBoxName.Text != DISPLAY_NAME) || (txtBoxName.Text == ""))
                {
                    //txtBoxName.Text.Replace(txtBoxName.Text, dogName);
                    txtBoxName.Text = dogName;
                    txtBoxName.Foreground = Brushes.Black;
                }
            }

        }

        private void txtBoxName_GotFocus(object sender, RoutedEventArgs e)
        {
            DisplayLstBoxDogNames();
        }

        private void txtBoxName_LostFocus(object sender, RoutedEventArgs e)
        {
            if (txtBoxName.Text == DISPLAY_NAME)
            {
                txtBoxName.Foreground = Brushes.Gray;
            }

            else if (txtBoxName.Text != DISPLAY_NAME)
            {
                txtBoxName.Foreground = Brushes.Gray;
            }
        }
    }
}