how to get checkbox checked items in datagrid in wpf

I want to get checked rows in the code behind ..i dont know how to get please help me..

in the xaml page i m having datagrid view with check box . when i m selecting mulitple check boxs and give submit button i want get rows where checkbox are selected in the code behind:

<GroupBox Header="Liste des entités" Margin="10,10,10,10" Grid.Row="1">
                <DataGrid x:Name="dgUsers" AutoGenerateColumns="False" >
                    <DataGrid.Columns>
                        <DataGridTemplateColumn>
                            <DataGridTemplateColumn.HeaderTemplate>
                                <DataTemplate>
                                    <CheckBox Name="hcb" Checked="hcb_Checked" Unchecked="hcb_Unchecked" Content="Select all" />
                                </DataTemplate>
                            </DataGridTemplateColumn.HeaderTemplate>
                            <DataGridTemplateColumn.CellTemplate>
                                <DataTemplate>
                                    <CheckBox Name="cb" Width="50"  IsChecked="{Binding  Path = c , Mode = TwoWay}" ></CheckBox>
                                </DataTemplate>
                            </DataGridTemplateColumn.CellTemplate>
                        </DataGridTemplateColumn>
                        <DataGridTextColumn Binding="{Binding logicName}" Header="Nom logique" ></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding displayName}" Header="Nom d'affichage"></DataGridTextColumn>
                    </DataGrid.Columns>
                </DataGrid>
            </GroupBox>