WPF: Using binding in C#

So to give you an Example, first create a Model

public class User
{
    public int ID { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }
}

then in your Code-Behind File create an ObservableCollection of that Model

private ObservableCollection<User> _myUsers;

    public ObservableCollection<User> MyUsers
    {
        get
        {
            if (_myUsers == null)
            {
                _myUsers = new ObservableCollection<User>();
            }
            return _myUsers;
        }
    }

and now you can bind your DataGrid to this Property

<DataGrid Grid.Row="1" Name="dataGridUser" ItemsSource="{Binding MyUsers}" AutoGenerateColumns="True"/>

and don´t forget to set the DataContext

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    DataContext="{Binding RelativeSource={RelativeSource Self}}"></Window>

if you add a new User to the ObservableCollection MyUsers it will immediately be displayed in your DataGrid, but if you change the FirstName of a existing User it will not display the changes. To do this you must implement INotityPropertyChanged in your Model.

But if you plan to develop a more complex Application I would recommend to take a look at the MVVM-Pattern.

Personally I like the MVVM Light Toolkit this Video should give you a good Idea what MVVM is all about.