i am working on POS application using SQL CE , WPF , Entity framework 3.5sp2 and iam trying to use data grid as my Order Entry Control for User to enter Products Order . Iam plannning to bind this to enitiy frmae work model , abd looking for 2 way updating ?

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        using (MasterEntities nwEntities = new MasterEntities())
        {
           var users = from d in nwEntities.Companies
                                 select new { d.CompanyId, d.CompanyName, d.Place };

              listBox1.DataContext = users;
              dataGrid1.DataContext = users;

             //   foreach (String c in customers)
             //  {
             //      MessageBox.Show(c.ToString());
             //  }
        }

      }

When try to double clikc on the datagrid it through s a error with

Caption " Invalid Operation Execption was unhandled " and

Message " A TwoWay or OneWayToSource binding cannot work on the read-only property 'CompanyId' of type '<>f__AnonymousType0`3[System.Int32,System.String,System.String]'.

whats wrong here

and my xaml coding goes like this

   <Grid>
     <ListBox Name="listBox1" ItemsSource="{Binding}"  />
    <Button Content="Show "  Name="button1" Click="button1_Click"  />

    <DataGrid AutoGenerateColumns="False" Name="dataGrid1" ItemsSource="{Binding}" >
      <DataGrid.Columns>
          <DataGridTextColumn Header=" ID"     Binding="{Binding CompanyId}"/>
          <DataGridTextColumn Header="Company Name"  Binding="{Binding CompanyName}"/>
          <DataGridTextColumn Header="Place"    Binding="{Binding Place}" />
        </DataGrid.Columns>
    </DataGrid>

</Grid>

EDITED :

i made the changes shown by @vorrtex, But, then i added another button to save the chages and in button click event i added follwing code , butit showing Updating error

  private void button2_Click(object sender, RoutedEventArgs e)
    {
         nwEntities.SaveChanges();
    }