Convert Postman code to regular C# code

var client = new RestClient("https://seller.digikala.com/Account/Login");
var request = new RestRequest(Method.POST);
request.AddHeader("postman-token", "0e4d8dba-29da-0b26-1b43-1bf974e9b5de");
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
IRestResponse response = client.Execute(request);

I can send request successfully and login to site in postman, but I can’t do it in VS. This is my code in VS:

var client = new RestClient("https://seller.digikala.com/Account/Login");

var request = new RestRequest(Method.POST);
request.AddParameter("IsPersistent", true, ParameterType.GetOrPost);
request.AddParameter("Password", "myPass", ParameterType.GetOrPost);
request.AddParameter("UserName", "myUsername", ParameterType.GetOrPost);
request.AddParameter("returnUrl", "/Account/Login", ParameterType.GetOrPost);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");

IRestResponse response = client.Execute(request);

but I get “unauthorized” message (401) in VS