Google Drive API C# - Create a folder

CreateFolder.cs

private static void CreateFolder(string folderName,DriveService service)
        {
            var fileMetadata = new Google.Apis.Drive.v3.Data.File()
            {
                Name = folderName,
                MimeType = "application/vnd.google-apps.folder"
            };
            var request = service.Files.Create(fileMetadata);
            request.Fields = "id";
            var file = request.Execute();
            Console.WriteLine("Folder ID: " + file.Id);

        }

what is Driveservice here and how to create

DriveService service = new DriveService(new BaseClientService.Initializer()
{
HttpClientInitializer = credential,
ApplicationName = "MyAppName",
});
service.HttpClient.Timeout = TimeSpan.FromMinutes(100);

I have only access token, how i can create DriveService object using access token

I have only access token, how i can create DriveService object using access token

GoogleCredential? credential = GoogleCredential.FromAccessToken(accessToken);
            DriveService service = new(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
            });