How to pass TextBox Values

Question

Hi

  How to pass textbox values instead of hardcode in below code

var request = new RestRequest(Method.POST);
 request.AddHeader("content-type", "application/json");

var body = @"{" + "\n" +
            @"    ""email"" : ""[email protected]""," + "\n" +
            @"    ""password"" : ""Tmp023""" + "\n" +
            @"}";

Thanks