Как отправить POST-запрос?

class Program
{
    private static readonly HttpClient _client = new HttpClient();

    static async Task Main(string[] args)
    {
        _client.DefaultRequestHeaders.UserAgent.ParseAdd("appp");

        Dictionary<string, string> data = new Dictionary<string, string>
        {
            ["grant_type"] = "refresh_token",
            ["client_id"] = "id",
            ["client_secret"] = "secret",
            ["refresh_token"] = "token"
        };
        try
        {
            string response = await PostFormAsync("https://shikimori.one/oauth/token", data);
            Console.WriteLine(response);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

        Console.WriteLine("Done.");
        Console.ReadKey();
    }

    public static async Task<string> PostFormAsync(string url, Dictionary<string, string> formData)
    {
        using var content = new FormUrlEncodedContent(formData);
        using var request = new HttpRequestMessage(HttpMethod.Post, url) { Content = content };
        using var response = await _client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead).ConfigureAwait(false);
        return await response.EnsureSuccessStatusCode().Content.ReadAsStringAsync();
    }
}