Cxz/Login.xaml

<Window x:Class="Learn.Login"
        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:Learn"
        mc:Ignorable="d"
        Title="Login" Height="450" Width="800">
    <Grid>
        <StackPanel>
            <TextBlock HorizontalAlignment="Center">Введите пароль</TextBlock>
            <GroupBox Header="Пароль">
                <PasswordBox Name="Pass"/>
            </GroupBox>
            <Button Click="GoAuth">ВХОД</Button>
        </StackPanel>
    </Grid>
</Window>