You do not specify anything, not even if it is a GET or POST, but this is an example from Postman using restsharp
var client = new RestClient("https://google.com");
var request = new RestRequest(Method.GET);
request.AddHeader("postman-token", "49bab31b-6be2-5862-e3ca-351cb8b35d86");
request.AddHeader("cache-control", "no-cache");
IRestResponse response = client.Execute(request);
solved Converting php to c#, curl to .net [closed]