title: Need to replace fixed value with string or text box value
body: <p>How can I replace the value \"username\" with the value of a text box or a string? </p>
  
  <pre><code>request.AddHeader("content-type", "application/json");
  request.AddParameter("application/json",
      "{\"myname\":\"username\",\n\"mypass\":\"password\"}", ParameterType.RequestBody);
  </code></pre>