Check out example codes for "c# post request". It will help you in understanding the concepts better.

Code Example 1

using System.Net.Http;
private static readonly HttpClient client = new HttpClient();
var values = new Dictionary<string, string>
{
    { "thing1", "hello" },
    { "thing2", "world" }
};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("http://www.example.com/recepticle.aspx", content);
var responseString = await response.Content.ReadAsStringAsync();

Code Example 2

private static readonly HttpClient client = new HttpClient();

var responseString = await client.GetStringAsync("http://www.example.com/recepticle.aspx");

Code Example 3

//You can aquire RestSharp from Nuget package manager
  RestClient restClient = 
  new RestClient(string.Format("{0}/myservice/api/endpoint", "https://exampledomain.com:88"));
  RestRequest request = new RestRequest(Method.POST);
  request.RequestFormat = DataFormat.Json;
  request.AddJsonBody(data); //data is C# model for post request
  request.AddHeader("Accept", "application/pdf");
  var result = restClient.Execute(request);

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