Binding String property to TextBox Text from Code Behind

Sorry for this basic question

I have a data model :

class data_test
    {
        public string textdata { get; set; }
        public bool booldata { get; set; }
        public bool checkdata { get; set; }
        public data_opt enumdata { get; set; }
    }

Here's Enum :

   enum data_opt
        {
            managed = 1,
            unmanaged = 2 ,
            mixed = 3
        }

Then I create a data model :

    var n_Data = new data_test()
    { textdata = "test data",
    booldata = false,
    checkdata = true ,
    enumdata = data_opt.mixed
    };

And I create a text box from code behind :

 var text_box = new TextBox();

Now I want to bind text_box.Text property to n_Data.textdata from code behind

The same way DataGrid works , two-way connection with real-time update.

I found some pages :

Binding String Property in Code-Behind TextBlock

WPF Data Binding to a string property

Binding string property to object

Unfortunately , none of them worked for me , Here's my code to bind:

Binding binding = new Binding();
binding.Path = new PropertyPath("textdata");
binding.Source = n_Data;
text_box.SetBinding(TextBlock.TextProperty, binding);

Also I tried this :

    Binding binding = new Binding();
    binding.Path = new PropertyPath("textdata");
    binding.Source = n_Data;
    BindingOperations.SetBinding(text_box, TextBlock.TextProperty, binding);

Both of them don't work , What am I doing wrong ?