Alex Gorbunov

public class TreeNode
    {
        public int ParentId { get; set; }
        public string Name { get; set; }
        public ObservableCollection<TreeNode> Children { get; set; }
    }

    public class TreeViewModel
    {
        public ObservableCollection<TreeNode> Nodes { get; set; }

        public TreeNode SelectedNode { get; set; }
    }

    public partial class MainWindow : Window
    {
        public TreeViewModel model { get; set; }

        private int i = 1;

        public MainWindow()
        {
            InitializeComponent();

            model = new TreeViewModel();

            model.Nodes = new ObservableCollection<TreeNode>();
            this.DataContext = model;

            model.Nodes.Add(new TreeNode() { Name = "Root", Children = new ObservableCollection<TreeNode>() });
            model.Nodes.FirstOrDefault().Children.Add(new TreeNode() { Name = "Second" });

        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            if (model.SelectedNode != null)
            {
                model.SelectedNode.Children.Add(new TreeNode() { Name = "Children "+i.ToString(), Children = new ObservableCollection<TreeNode>() });
            }
            else
            {
                model.Nodes.Add(new TreeNode() { Name = "Root "+i.ToString(), Children = new ObservableCollection<TreeNode>() });
            }
            i++;
        }

        private void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
        {
            model.SelectedNode = (TreeNode)e.NewValue;
        }
    }

<Grid>
        <TreeView HorizontalAlignment="Left" Height="337" Margin="42,34,0,0" VerticalAlignment="Top" Width="303" ItemsSource="{Binding Path=Nodes}">
            <TreeView.ItemTemplate>
				<HierarchicalDataTemplate ItemsSource="{Binding Children}">
					<TextBlock Text="{Binding Name}" />
				</HierarchicalDataTemplate>
			</TreeView.ItemTemplate>
        </TreeView>
        <Button Content="Button" HorizontalAlignment="Left" Margin="374,34,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
    </Grid>

1. Использовать для привязываемых коллекций - ObservableCollection - умеет оповещать подписчика об изменении коллекции
2. WPF не умеет привязывает SelectedItem у TreeView, решения- https://stackoverflow.com/questions/7153813/wpf-mv... , https://tyrrrz.me/blog/wpf-treeview-selecteditem-t...

Первые 2 класса хранят данные, загружают из бд, ну тут сами придумаете. См LoadData
Последний это форма обрабатываются события NodeMouseClick и TextChanged на текст боксах.
Логика простейшая, но это в общем то пример, в реальности усложните по вкусу.

using System.Collections.Generic;

namespace TreeViewBinding.Code
{
    public class TreeSource
    {
        public TreeSource()
        {
            Leaves = new List<TreeLeaf>();
        }
        public List<TreeLeaf> Leaves { get; set; }

        /// <summary>
        /// Load data stub. In this example use mock data. In real application load data from database or web service
        /// </summary>
        public void LoadData()
        {
            var first = new TreeLeaf { Description = "First description", Title = "First" };
            var firstSubs = new[]
            {
                new TreeLeaf(first){Description = "First desc",Title = "First"},
                new TreeLeaf(first){Description = "Second desc",Title = "Second"},
                new TreeLeaf(first){Description = "Third desc",Title = "Third"}
            };
            first.Leaves.AddRange(firstSubs);
            var second = new TreeLeaf { Description = "Second description", Title = "Second" };
            var third = new TreeLeaf { Description = "Third description", Title = "Third" };
            Leaves.AddRange(new[]
            {
                first,
                second,
                third,
            });
        }
    }
}

using System.Collections.Generic;

namespace TreeViewBinding.Code
{
    public class TreeLeaf
    {
        public TreeLeaf(TreeLeaf parent = null)
        {
            Leaves = new List<TreeLeaf>();
            Parent = parent;
        }
        public int Id { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string Icon { get; set; }
        public List<TreeLeaf> Leaves { get; private set; }
        public TreeLeaf Parent { get; private set; }
    }
}

#region License
// // Разработано: Коротенко Владимиром Николаевичем (Vladimir N. Korotenko)
// // email: koroten@ya.ru
// // skype:vladimir-korotenko
// // https://vkorotenko.ru
// // Создано:  09.05.2020 8:26
#endregion

using System.Collections.Generic;
using System.Windows.Forms;
using TreeViewBinding.Code;

namespace TreeViewBinding
{
    public partial class TreeViewBindingForm : Form
    {
        private TreeSource _treeSource;
        private TreeLeaf _currentLeaf;
        private TreeNode _node;
        public TreeViewBindingForm()
        {
            InitializeComponent();
            _treeSource = new TreeSource();
            _treeSource.LoadData();
            FillInTree(treeView.Nodes, _treeSource.Leaves);
        }

        private static void FillInTree(TreeNodeCollection  nodes, IEnumerable<TreeLeaf> leafs)
        {
            foreach (var leaf in leafs)
            {
                var treeNode = new TreeNode(leaf.Title) {Tag = leaf};
                nodes.Add(treeNode);
                if (leaf.Leaves.Count > 0) FillInTree(treeNode.Nodes, leaf.Leaves);
            }
        }

        private void treeView_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            if (e.Node.Tag is TreeLeaf item)
            {
                _node = e.Node;
                _currentLeaf = item;
                titleTextBox.Text = item.Title;
                descriptionTexBox.Text = item.Description;
            }
        }

        private void titleTextBox_TextChanged(object sender, System.EventArgs e)
        {
            if (_node != null)
            {
                _currentLeaf.Title = _node.Text = titleTextBox.Text;
            }
        }

        private void descriptionTexBox_TextChanged(object sender, System.EventArgs e)
        {
            if (_node != null)
            {
                _currentLeaf.Description = descriptionTexBox.Text;
            }
        }
    }
}