here is the code where i have and error in "!Menu" adn other parts and i pste it from a book of microsoft

<Window x:Class="Browser"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="My Own Wpf Browser" Height="480" Width="640" Name="Browser"
    Icon="face02.ico" SizeToContent="WidthAndHeight"
    WindowStartupLocation="CenterScreen"   >
    
   <Grid Name="grid1">
    <DockPanel x:Uid="DockPanel_1">
        < !Menu Bar>
        <Menu x:Uid="Menu_1" Background="White" Name="_MainMenu" DockPanel.Dock="Top">
            <! Navigate Menu>
            <MenuItem x:Uid="NavigateMenu" Header="_Navigate" />
                <! Help Menu>
                <MenuItem x:Uid="HelpMenu" Header="_Help">
                    <MenuItem x:Uid="AboutMenu" Header="_About" />
                    </MenuItem>
        </Menu>
    </DockPanel>
    </Grid>

</Window>