<DataGrid AutoGenerateColumns="True" 
                  EnableRowVirtualization="True" 
                  ItemsSource="{Binding}"
                  Name="usersDataGrid" 
                  RowDetailsVisibilityMode="VisibleWhenSelected"/>

    public class MainWindowViewModel
    {
        .................................................................................
        public System.Windows.Data.CollectionViewSource cvsUsers;
        ................................................................................ 
        public MainWindowViewModel()
        {
            dbDataSet = new db1DataSet();

            db1DataSetUsersTableAdapter = new TryMVVM.db1DataSetTableAdapters.UsersTableAdapter();
            db1DataSetUsersTableAdapter.Fill(dbDataSet.Users);

            cvsUsers=new System.Windows.Data.CollectionViewSource();
            cvsUsers.Source = dbDataSet.Users;
            cvsUsers.View.MoveCurrentToFirst(); // Ничего не происходит
        }

    }

    public partial class MainWindow : Window
    {
        public MainWindowViewModel MainWinVM;
        
        public MainWindow()
        {
            InitializeComponent();
            MainWinVM=new MainWindowViewModel() ;
            this.usersDataGrid.DataContext = MainWinVM.cvsUsers;
        }

    }