I am bindind rss items from the net to this page, I cannot Seem to navigate to the link of a selected items hyper link which through binding is string.

can anyone help me to navigate to weblink from a listbox item when selected ???

<ListBox Height="712" HorizontalAlignment="Left" Name="listNews" VerticalAlignment="Top" Width="468" SelectionChanged="listNews_SelectionChanged" Margin="0,-22,0,0">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" Height="132">
                <Image Source="{Binding Avatar}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,7,5,0"/>
                <StackPanel Width="370">   
                    <TextBlock Text="{Binding Newstitle}" TextWrapping="Wrap" Foreground="#FFC8AB14" FontSize="28" />
                    <HyperlinkButton Name="{Binding NewsLink}" Content="{Binding NewsLink}" NavigateUri="{Binding NewsLink}" FontSize="18" ClickMode="Press" Click="Selected" />
                </StackPanel>
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>


   private void listNews_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        WebBrowserTask webBrowserTask = new WebBrowserTask();
        webBrowserTask.URL = **???????;**

        webBrowserTask.Show();