public class UserFacade
{
    HttpClient _client;
    string url = "http://localhost:50759/api/v1/login";
    public void LoginUser(string userName, string password)
    {
        _client = new HttpClient
        {
            BaseAddress = new Uri(url)
        };

        _client.DefaultRequestHeaders.Accept.Clear();
        _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

        var model = new UserModel
        {
            UserName = userName,
            UserPassword = password
        };

        var userModel = JsonConvert.SerializeObject(model);
        var content = new StringContent(userModel, Encoding.UTF8, "application/json");

        GetUserTask(_client, content).Wait();

    }

    private async Task GetUserTask(HttpClient client, StringContent content)
    {
        using (client)
        {
            HttpResponseMessage res = await client.PostAsync(url, content);
            res.EnsureSuccessStatusCode();
            if (res.IsSuccessStatusCode)
            {
                var response = await res.Content.ReadAsStringAsync();

                JavaScriptSerializer JSserializer = new JavaScriptSerializer();
                //deserialize to your class
                //var userResponse = JSserializer.Deserialize<UserResponse>(response);

            }
        }
    }

}

private async Task GetUserTask(HttpClient client, StringContent content)
{
    using (client)
    {
        HttpResponseMessage res = await client.PostAsync(url, content).ConfigureAwait(false);
        res.EnsureSuccessStatusCode();
        if (res.IsSuccessStatusCode)
        {
            var response = await res.Content.ReadAsStringAsync().ConfigureAwait(false);
        }
    }
}