How to read/write RAPID?

Sorry, can somebody explain

  1. What means “myString”
    RapidData rd = _controller.Rapid.GetRapidData(“T_ROB1”, “myModule”, “myString”);

  2. what I should put inside the Textbox for writing RAPID ?
    rapidString.FillFromString( textBoxString.Text);

I need just an alive example.

  1. The variable inside the module you are calling

I believe the manual for the Robot Application Builder would be of use to you, specifically section 5.5.3.1. “Working with Rapid Data”