Zachet/DB/Pages/AddChangePage.xaml

<Page x:Class="DB.Pages.AddChangePage"
      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:DB.Pages"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Title="AddChangePage">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition Height="30"></RowDefinition>
        </Grid.RowDefinitions>
        <StackPanel Orientation="Vertical">
            <GroupBox Header="Заголовок">
                <TextBox Name="TBTitle"></TextBox>
            </GroupBox>
            <GroupBox Header="Цена">
                <TextBox Name="TBCost"></TextBox>
            </GroupBox>
        </StackPanel>
        <Button Name="BTNDio" Grid.Row="1" Click="BTNDio_Click">Add</Button>
    </Grid>
</Page>