demoekz/Cafe/AddOnShiftPage.xaml

<Page x:Class="Cafe.AddOnShiftPage"
      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:Cafe"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Title="AddOnShiftPage">

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <StackPanel HorizontalAlignment="Left" VerticalAlignment="Center" Grid.Column="1">
            <ComboBox Margin="10" Name="Waiter1" DisplayMemberPath="Surname" SelectedValuePath="Surname" SelectedIndex="0"></ComboBox>
            <ComboBox Margin="10"  Name="Waiter2" DisplayMemberPath="Surname" SelectedValuePath="Surname"  SelectedIndex="0"></ComboBox>
            <ComboBox Margin="10"  Name="Cook" DisplayMemberPath="Surname" SelectedValuePath="Surname"  SelectedIndex="0"></ComboBox>
        </StackPanel>
        <StackPanel HorizontalAlignment="Right" VerticalAlignment="Center" Grid.Column="0">
            <TextBlock Margin="10" >Waiter #1</TextBlock>
            <TextBlock Margin="10" >Waiter #2</TextBlock>
            <TextBlock Margin="10" >Cook</TextBlock>
        </StackPanel>

        <Button Grid.ColumnSpan="2" Height="35" Width="85" HorizontalAlignment="Center" VerticalAlignment="Bottom" Margin="10" Name="AddOnShiftBtn" Click="AddOnShiftBtn_Click">Add on shift</Button>
    </Grid>
</Page>