var document = new BsonDocument
                {
                    { "name", "MongoDB" },
                    { "type", "Database" },
                    { "count", 1 },
                    { "LastModifiedDate", DateTime.UtcNow},
                    { "info", new BsonDocument
                        {
                            { "x", 203 },
                            { "y", 102 }
                        }}
                };

                collection.InsertOne(document);

 var user = new User("Billy", "billgates@ms.com", DateTime.Now);
                collection.InsertOne(user.ToBsonDocument());

 public class User
    {
        public User(string fullname, string email)
        {
            Fullname = fullname;
            Email = email;
            LastModifiedDate = DateTime.Now;
        }
        public User(string fullname, string email, DateTime lastModified)
        {
            Fullname = fullname;
            Email = email;
            LastModifiedDate = lastModified;
        }

        public string Fullname { get; }
        public string Email { get; }
        public DateTime LastModifiedDate { get; }
    }