Вывести текст в TextBlock

public MainWindow()
        {
            InitializeComponent();
 
            StackPanel sp = new StackPanel();
            sp.Orientation = System.Windows.Controls.Orientation.Horizontal;
            sp.HorizontalAlignment = System.Windows.HorizontalAlignment.Stretch;
            sp.VerticalAlignment = System.Windows.VerticalAlignment.Center;
 
            TextBlock textBlock2 = new TextBlock();
 
            textBlock2.Text = "Скачивание списка md5 файлов сервера, так как он старый";
            sp.Children.Add(textBlock2);
        }

public class RelayCommand<T> : ICommand
{
    private readonly Action<T> _execute;
    private readonly Func<T, bool> _canExecute;
 
    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }
    public RelayCommand(Action<T> execute, Func<T, bool> canExecute = null)
    {
        _execute = execute;
        _canExecute = canExecute;
    }
    public bool CanExecute(T parameter)
        => _canExecute?.Invoke(parameter) ?? true;
 
    public void Execute(T parameter)
        => _execute(parameter);
}

public bool CanExecute(T parameter)
    => _canExecute?.Invoke(parameter) ?? true;

public bool CanExecute(T parametr)
{
    return _canExecute == null || _canExecute(T parametr);
}

using System;
using System.Windows.Input;
 
namespace VModels
{
    public class RelayCommand : ICommand
    {
        private readonly Action<object> _execute;
        private readonly Func<object, bool> _canExecute;
 
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
        public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
        {
            this._execute = execute;
            this._canExecute = canExecute;
        }
        public bool CanExecute(object parametr)
        {
            return this._canExecute == null || this._canExecute(parametr);
        }
        public void Execute(object parametr)
        {
            this._execute(parametr);
        }
    }
 
    public class RelayCommand<T> : ICommand
    {
        private readonly Action<T> _execute;
        private readonly Func<T, bool> _canExecute;
 
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
        public RelayCommand(Action<T> execute, Func<T, bool> canExecute = null)
        {
            _execute = execute;
            _canExecute = canExecute;
        }
        public bool CanExecute(T parameter)
            => _canExecute?.Invoke(parameter) ?? true;
 
        public void Execute(T parameter)
            => _execute(parameter);
 
        public bool CanExecute(object parameter)
            => CanExecute(parameter is T t ? t : default);
 
        public void Execute(object parameter)
            => Execute(parameter is T t ? t : default);
    }
}

// Команда в VM
private void ReportDrawDetailsExecuted(DrawReport drawReport)
{
    WindowService.ShowWindow(new DrawDetailsReportWindowVM(drawReport));
}
private static bool ReportDrawDetailsCanExecute(DrawReport arg) => arg != null;
 
// Вызов команды
public ICommand ReportDrawDetailsCommand => _reportDrawDetailsCommand ??
    (_reportDrawDetailsCommand = new RelayCommand<DrawReport>(ReportDrawDetailsExecuted, ReportDrawDetailsCanExecute));

public ICommand MyCommand {get;}

public RelayCommand MyCommand {get;}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Simplified; // Это пространство с классами BaseInpc и RelayCommand
using System.Diagnostics;
using System.Threading;
 
namespace LauncherWPFtest
{
    public class TimerViewModel : BaseInpc
    {
        private double _seconds;
 
        public double Seconds { get => _seconds; private set => Set(ref _seconds, value); }
 
        private readonly Stopwatch stopwatch = new Stopwatch();
        private readonly Timer timer;
 
        public TimerViewModel()
        {
            timer = new Timer(_ => Seconds = stopwatch.Elapsed.TotalSeconds, null, 100, 100);
            stopwatch.Start();
        }
 
        private RelayCommand _stopCommand;
        public RelayCommand StopCommand => _stopCommand
            ?? (_stopCommand = new RelayCommand(
                () => stopwatch.Stop(),
                () => stopwatch.IsRunning));
 
        private RelayCommand _startCommand;
        public RelayCommand StartCommand => _startCommand
            ?? (_startCommand = new RelayCommand(
                () => stopwatch.Start(),
                () => !stopwatch.IsRunning));
 
        private RelayCommand _resetCommand;
        public RelayCommand ResetCommand => _resetCommand
            ?? (_resetCommand = new RelayCommand(
                () => stopwatch.Reset(),
                () => !stopwatch.IsRunning && stopwatch.ElapsedTicks > 0));
    }
 
}

        public RelayCommand StopCommand => _stopCommand
            ?? (_stopCommand = new RelayCommand(
                _ => stopwatch.Stop(),
                _ => stopwatch.IsRunning));

 #region Делегаты для методов WPF команд
    public delegate void ExecuteHandler(object parameter);
    public delegate bool CanExecuteHandler(object parameter);
    #endregion
 
     #region Класс команд - RelayCommand
   // / <summary>Класс реализующий<see cref="ICommand"/>.<br/>
   // / Реализация взята из<see href="https://www.cyberforum.ru/wpf-silverlight/thread2390714-page4.html#post13535649"/>
   // / и дополнена конструктором для методов без параметра.</summary>
    public class RelayCommand : ICommand
    {
        private readonly Action<object> _execute;
        private readonly Func<object, bool> _canExecute;
 
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
        public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
        {
            this._execute = execute;
            this._canExecute = canExecute;
        }
        public bool CanExecute(object parametr)
        {
            return this._canExecute == null || this._canExecute(parametr);
        }
        public void Execute(object parametr)
        {
            this._execute(parametr);
        }
    }
    #endregion