R29/WpfApp29/TaskCreationWindow.xaml

<Window x:Class="WpfApp29.TaskCreationWindow"
        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:WpfApp29"
        mc:Ignorable="d"
        Title="TaskCreationWindow" Height="450" Width="800">
    <Window.Background>
        <ImageBrush ImageSource="/bg.png"/>
    </Window.Background>
    <Grid>
        <Border Padding="20" VerticalAlignment="Center" HorizontalAlignment="Center" Background="#E5ECCC74"
                BorderThickness="6" CornerRadius="30" BorderBrush="#FF312B04" Height="300" Grid.RowSpan="2">
            <Grid>

                <Grid.RowDefinitions>
                    <RowDefinition></RowDefinition>
                    <RowDefinition></RowDefinition>
                    <RowDefinition></RowDefinition>
                    <RowDefinition></RowDefinition>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="130"></ColumnDefinition>
                    <ColumnDefinition></ColumnDefinition>
                </Grid.ColumnDefinitions>

                <!--Надпись "Вход в личный кабинет"-->
                <Label Content="Добавление нового задания" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="24" 
                       FontFamily="Copperplate Gothic Bold" Grid.ColumnSpan="2"></Label>

                <!--Поле для ввода названия задания-->
                <Label Content="Название задания" HorizontalAlignment="Center" VerticalAlignment="Center"  Grid.Row="1" Grid.Column="0"></Label>
                <TextBox Name="TbTaskName" Width="200" Height="40" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Row="1" Grid.Column="1"></TextBox>

                <!--Поле для ввода описания задания-->
                <Label Content="Описание задания" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Row="2" Grid.Column="0"></Label>
                <TextBox Name="TbTaskDesc"  Width="200" Height="40" HorizontalAlignment="Center" VerticalAlignment="Center"
                             Grid.Row="2" Grid.Column="1"></TextBox>

                <!--Кнопка добавления задания-->
                <Button Name="ButtonAddNewTask" Width="220" Height="40" HorizontalAlignment="Center" VerticalAlignment="Center" 
                        Content="Добавить задание" BorderBrush="#FF5A5205" 
                        Grid.Row="4" Grid.Column="1" Click="ButtonAddNewTask_Click"></Button>

                <!--Кнопка отмены добавления задания-->
                <Button Name="ButtonGoBack"  Width="110" Height="40" HorizontalAlignment="Center" VerticalAlignment="Center" 
                        Content="Отмена" BorderBrush="#FF5A5205" 
                        Grid.Row="4" Grid.Column="0" Click="ButtonGoBack_Click"></Button>

            </Grid>
        </Border>

    </Grid>
</Window>