[c#] How to create JSON post to api using C#

I'm in the process of creating a C# console application which reads text from a text file, turns it into a JSON formatted string (held in a string variable), and needs to POST the JSON request to a web api. I'm using .NET Framework 4.

My struggle is with creating the request and getting the response, using C#. What is the basic code that is necessary? Comments in the code would be helpful. What I've got so far is the below, but I'm not sure if I'm on the right track.

//POST JSON REQUEST TO API
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("POST URL GOES HERE?");

request.Method = "POST";
request.ContentType = "application/json";

System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
byte[] bytes = encoding.GetBytes(jsonPOSTString);

request.ContentLength = bytes.Length;

using (Stream requestStream = request.GetRequestStream())
{
    // Send the data.
    requestStream.Write(bytes, 0, bytes.Length);
}

//RESPONSE HERE

Try using Web API HttpClient

    static async Task RunAsync()
    {
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://domain.com/");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


            // HTTP POST
            var obj = new MyObject() { Str = "MyString"};
            response = await client.PostAsJsonAsync("POST URL GOES HERE?", obj );
            if (response.IsSuccessStatusCode)
            {
                response.//.. Contains the returned content.
            }
        }
    }

You can find more details here Web API Clients