StTest/MyTests/Authorization.xaml

<Page x:Class="MyTests.Authorization"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:MyTests"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Height="475" Width="475">
    <Grid>
        <Button Content="Войти" Margin="0,250,15,0" VerticalAlignment="Top" Width="93" Click="Auth" Height="26" FontSize="18"/>
        <TextBox x:Name="Login" LostFocus="LostLogin" GotFocus="LoginFocus" Margin="0,150,15,0" TextWrapping="Wrap" Text ="Логин" VerticalAlignment="Top" Width="145" Height="25" FontSize="16" />
        <PasswordBox x:Name="Password" LostFocus="LostPassword" GotFocus="PasswordFocus" Margin="0,210,15,0" Password ="Password" VerticalAlignment="Top" Width="126"/>
    </Grid>
</Page>