so i have created a listview with grouping and i want a image that are binded to that group 's expander how do i do that
xaml for the expander
Code:
                                                        <Expander.Background>
                                                            <ImageBrush ImageSource="{Binding billed}"/>
                                                        </Expander.Background>
xaml list view
Code:
                    <ListView x:Name="hjuldata" Background="#FF303030" BorderBrush="#FF303030" Foreground="#FF00B408">
                        <ListView.View>
                            
                            <GridView>
                                <GridView.ColumnHeaderContainerStyle>
                                    <Style TargetType="{x:Type GridViewColumnHeader}">

                                        <Setter Property="Background" Value="Black" />
                                        <Setter Property="Foreground" Value="#FFEAEAEA                                                 " />
                                        <Setter Property="FontWeight" Value="Bold" />
                                    </Style>
                                </GridView.ColumnHeaderContainerStyle>
                                <GridViewColumn Header=" "  DisplayMemberBinding="{Binding billed}" />
                                <GridViewColumn Header="Model" Width="120" DisplayMemberBinding="{Binding Model}" />
                                <GridViewColumn Header="Årgang" Width="120" DisplayMemberBinding="{Binding Årgang}" />
                                <GridViewColumn Header="Krydsmål" Width="130" DisplayMemberBinding="{Binding Krydsmål}" />
                                <GridViewColumn Header="ET" Width="50" DisplayMemberBinding="{Binding ET}" />
                                <GridViewColumn Header="Centerhul" Width="120" DisplayMemberBinding="{Binding centerhul}" />
                                <GridViewColumn Header="Hjulbolter" Width="120" DisplayMemberBinding="{Binding bolter}" />
                            </GridView>
                        </ListView.View>

                        <ListView.GroupStyle>
                            <GroupStyle>
                                <GroupStyle.ContainerStyle>
                                    <Style TargetType="{x:Type GroupItem}">
                                        <Setter Property="Template">
                                            <Setter.Value>
                                                <ControlTemplate>
                                                    <Expander IsExpanded="True" >
                                                        <Expander.Background>
                                                            <ImageBrush ImageSource="{Binding billed}"/>
                                                        </Expander.Background>
                                                        <Expander.Header>
                                                            <StackPanel Orientation="Horizontal">
                                                                <Image Source="{Binding billed}"  Stretch="Fill" ToolTip="Add tooltip"/>
                                                                <TextBlock Text="{Binding Name}" FontWeight="Bold" Foreground="#FFEAEAEA" FontSize="22" VerticalAlignment="Bottom"/>
                                                                <TextBlock Text="{Binding ItemCount}" FontSize="22" Foreground="Green" FontWeight="Bold" FontStyle="Italic" Margin="10,0,0,0" VerticalAlignment="Bottom" />
                                                                <TextBlock Text=" Antal" FontSize="22" Foreground="#FFEAEAEA" FontStyle="Italic" VerticalAlignment="Bottom" />
                                                            </StackPanel>
                                                        </Expander.Header>
                                                        <ItemsPresenter />
                                                    </Expander>
                                                </ControlTemplate>
                                            </Setter.Value>
                                        </Setter>
                                    </Style>
                                </GroupStyle.ContainerStyle>
                            </GroupStyle>
                        </ListView.GroupStyle>
                    </ListView>
c# code
Code:
public enum Mærke { Alfa_Romeo, Audi };

public class biler
{
        public string billed { get; set; }

        public string Model { get; set; }

        public string Type { get; set; }

        public string Årgang { get; set; }
        
        public string Krydsmål { get; set; }

        public int ET { get; set; }

        public string centerhul { get; set; }

        public string bolter { get; set; }

        public string hjul { get; set; }

        public Mærke mærke { get; set; }
    }


                   List<biler> items = new List<biler>();
        items.Add(new biler() { Model = "166",  Årgang = "98-06", Krydsmål = "5x108", ET = 41, centerhul = "58,1", bolter = "B12x1,25",  mærke = Mærke.Alfa_Romeo});
        items.Add(new biler() { Model = "146", Årgang = "94-", mærke = Mærke.Alfa_Romeo });
        items.Add(new biler() { Model = "100", Årgang = "83-90", mærke = Mærke.Audi });
        hjuldata.ItemsSource = items;

        CollectionView view = (CollectionView)CollectionViewSource.GetDefaultView(hjuldata.ItemsSource);
        PropertyGroupDescription groupDescription = new PropertyGroupDescription("mærke");
        view.GroupDescriptions.Add(groupDescription);
        }