rkis1/WpfApp4/Views/MainWindow.xaml

<Window x:Class="WpfApp4.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp4"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid Background="Black">
        <TextBox HorizontalAlignment="Center" Margin="0,225,0,0" TextWrapping="Wrap" Text="{Binding User.Login}" VerticalAlignment="Top" Width="120"/>
        <TextBox HorizontalAlignment="Center" Margin="0,262,0,0" TextWrapping="Wrap" Text="{Binding User.Password}" VerticalAlignment="Top" Width="120" />
        <TextBlock HorizontalAlignment="Left" Margin="284,227,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Background="White"><Run Language="ru-ru" Text="Логин"/></TextBlock>
        <TextBlock HorizontalAlignment="Left" Margin="284,263,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Background="White" Height="17"><Run Language="ru-ru" Text="Пароль"/><LineBreak/><Run Language="ru-ru"/></TextBlock>
        <Button Content="Войти" HorizontalAlignment="Center" Margin="0,291,0,0" VerticalAlignment="Top" Command="{Binding Welcom}"/>
        <Button Content="Регистрация" HorizontalAlignment="Center" Margin="0,327,0,0" Command="{Binding Registration}" VerticalAlignment="Top" Click="Button_Click"/>

    </Grid>
</Window>