我在WPF中创建了一个带有数据绑定的组合框。我不知道如何将值设置为“comboboxselecteditem”

This is my Xaml code

这是我的Xaml代码

<Grid>
    <ComboBox Name="C1"  ItemsSource="{Binding}" HorizontalAlignment="Left" Margin="126,127,0,0" VerticalAlignment="Top" Width="218" SelectionChanged="C1_SelectionChanged" >

        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Margin="2"  Text="{Binding CUS_DESCRIPTION}" />
            </DataTemplate>
        </ComboBox.ItemTemplate>
        <ComboBox.ItemContainerStyle>
            <Style TargetType="{x:Type ComboBoxItem}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate>
                            <Grid x:Name="gd"  TextElement.Foreground="Black">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition/>
                                    <ColumnDefinition/>
                                    <ColumnDefinition/>
                                </Grid.ColumnDefinitions>
                                <TextBlock Margin="5" Grid.Column="0" Text="{Binding CUSTOMER_NAME}"/>
                                <TextBlock Margin="5" Grid.Column="1" Text="{Binding CUS_DESCRIPTION}"/>
                            </Grid>
                            <ControlTemplate.Triggers>
                                <Trigger Property="ComboBoxItem.IsSelected" Value="True">
                                    <Setter TargetName="gd"  Property="Background" Value="Gray"></Setter>
                                    <Setter TargetName="gd"  Property="TextElement.Foreground" Value="White"></Setter>
                                </Trigger>
                                <Trigger Property="ComboBoxItem.IsMouseOver" Value="True">
                                    <Setter TargetName="gd"  Property="Background" Value="Blue"></Setter>
                                    <Setter TargetName="gd"  Property="TextElement.Foreground" Value="White"></Setter>
                                </Trigger>

                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </ComboBox.ItemContainerStyle>
    </ComboBox>
</Grid>
<Grid>