I want to send sms using TheTexting.com

Question

I want to send a sms using TheTexting SMS API , I have created an account on the site and it shows that i have five free sms I created a web form and a button on that form on button click i paste the following code 

var client = new RestClient("https://www.thetexting.com/rest/sms/json/message/send");
var request = new RestRequest(Method.POST); request.AddHeader("content-type", "application/x-www-form-urlencoded"); request.AddHeader("cache-control", "no-cache"); request.AddParameter("application/x-www-form-urlencoded", "api_secret=j5hsuac8f6mdzdd&api_key=kve13qwq50p7xa2&from=987654321&to=123456789&text=Sample%20Message%20Text&type=text", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

 

check the reference

https://www.thetexting.com/Area/Documentation/SampleSendMessage

My username is danish47 and password is pakistan 

it is not sending any text can anybody help me out . I have give the credentials can anybody check either the Api is sending text or not