WPF menu (design)

//Tela de login//

<Window x:Class="ProvaWPF.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Login" Height="350" Width="525"
        Background="#FFE0DADA">

    <Grid>

        <Label Content="Usuário"
               HorizontalAlignment="Left"
               VerticalAlignment="Top"
               Margin="60,67,0,0"
               Height="37"
               Width="82"
               FontSize="20" />
        <TextBox HorizontalAlignment="Left"
                 Height="23"
                 Margin="174,78,0,0"
                 TextWrapping="Wrap"
                 Text=""
                 VerticalAlignment="Top"
                 Width="219" />
        <Label Content="Senha"
               HorizontalAlignment="Left"
               Margin="60,125,0,0"
               VerticalAlignment="Top"
               RenderTransformOrigin="-0.11,0.526"
               FontSize="20"
               Height="43"
               Width="92" />
        <TextBox HorizontalAlignment="Left"
                 Height="23"
                 Margin="174,136,0,0"
                 TextWrapping="Wrap"
                 Text=""
                 VerticalAlignment="Top"
                 Width="219" />
        <Button Content="Entrar"
                HorizontalAlignment="Left"
                Margin="174,190,0,88"
                VerticalAlignment="Center"
                Width="219"
                Height="42"
                FontSize="20" />
        <TextBlock HorizontalAlignment="Left"
                   Margin="60,265,0,0"
                   TextWrapping="Wrap"
                   Text="Novo usuário?"
                   VerticalAlignment="Top"
                   RenderTransformOrigin="0.787,0.747"
                          />

    </Grid>
</Window>

//Tela de Cadastro//

<Window x:Class="ProvaWPF.UI.Cadastro_de_usuario"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Cadastro_de_usuario" Height="350" Width="525">

    <Grid Background="#FFDCD9D9">

        <Label Content="Usuário"
               HorizontalAlignment="Left"
               VerticalAlignment="Top"
               Margin="60,67,0,0"
               Height="37"
               Width="82"
               FontSize="20" />
        <TextBox HorizontalAlignment="Left"
                 Height="23"
                 Margin="174,78,0,0"
                 TextWrapping="Wrap"
                 Text=""
                 VerticalAlignment="Top"
                 Width="219" />
        <Label Content="Senha"
               HorizontalAlignment="Left"
               Margin="60,125,0,0"
               VerticalAlignment="Top"
               RenderTransformOrigin="-0.11,0.526"
               FontSize="20"
               Height="43"
               Width="92" />
        <TextBox HorizontalAlignment="Left"
                 Height="23"
                 Margin="174,136,0,0"
                 TextWrapping="Wrap"
                 Text=""
                 VerticalAlignment="Top"
                 Width="219" />
        <Button Content="Incluir"
                HorizontalAlignment="Left"
                Margin="174,190,0,88"
                VerticalAlignment="Center"
                Width="219"
                Height="42"
                FontSize="20" />



    </Grid>
</Window>

//Tela Principal//

<Window x:Class="ProvaWPF.UI.Tela_principal"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Tela_principal" Height="350" Width="525">

    <Grid
          Background="#FF817C7C">
        <Menu Name="Menu"
            HorizontalAlignment="Left"
              Height="27"
              VerticalAlignment="Top"
              Width="85"
              Background="Gray"
              />
        <Menu>
        <MenuItem Header="_Sair"
                  Background="#FFD3C9C9" />

            <MenuItem Header="_Novo usuário"
                      Background="#FFCBC8C8" />
        </Menu>
        <Label Content="Usuário logado: "
               HorizontalAlignment="Left"
               Margin="27,49,0,0"
               VerticalAlignment="Top"
               FontSize="18" />
        <TextBlock HorizontalAlignment="Left"
                   Margin="193,54,0,0"
                   TextWrapping="Wrap"
                   Text="Usuário_1"
                   VerticalAlignment="Top"
                   FontSize="18"
                   FontWeight="Bold" />
        <Grid HorizontalAlignment="Left"
              Height="197"
              Margin="10,100,0,0"
              VerticalAlignment="Top"
              Width="497"
              Background="#FFC7C4C4">

        </Grid>

    </Grid>
</Window>