from stable_baselines3.common.torch_layers import BaseFeaturesExtractor

class MyNN(BaseFeaturesExtractor):
  """
  :param observation: (gym.Space)
  :parma features_dim: (int) Number of features extracted.
  """
  def __init__(self, observation, features_dim):
	super(MyNN, self).__init__(observation_space, features_dim)

	... # パラメータを書く

  def forward(self, x):
	... # ネットワークの接続を書く

model = DQN('NAMING_PARAM', 
			m_env: Monitor, 
			policy_kwargs=policy_kwargs,
            gamma, 
			learning_rate,
            learning_starts, 
			target_update_interval, 
			exploration_fraction, 
			tau
			)

# 学習
model.learn(total_timesteps)