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

Code Example 1

Uri u = new Uri("http://localhost:31404/Api/Customers");
            var payload = "{\"CustomerId\": 5,\"CustomerName\": \"Pepsi\"}";

            HttpContent c = new StringContent(payload, Encoding.UTF8, "application/json");
            var t = Task.Run(() => PostURI(u, c));
            t.Wait();

            Console.WriteLine(t.Result);
            Console.ReadLine();

Code Example 2

private static async Task PostBasicAsync(object content, CancellationToken cancellationToken)
{
    using (var client = new HttpClient())
    using (var request = new HttpRequestMessage(HttpMethod.Post, Url))
    {
        var json = JsonConvert.SerializeObject(content);
        using (var stringContent = new StringContent(json, Encoding.UTF8, "application/json"))
        {
            request.Content = stringContent;

            using (var response = await client
                .SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken)
                .ConfigureAwait(false))
            {
                response.EnsureSuccessStatusCode();
            }
        }
    }
}

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