It seems you're trying to import and use the `pytorch_lightning` module in your Python code, but Python cannot find the module because it is not installed in your environment. PyTorch Lightning is a lightweight PyTorch wrapper that helps you scale your models and write less boilerplate code. You can install it using Python's package manager, pip. Open your command line interface (CLI) and run the following command: ```shell pip install pytorch-lightning ``` If you are using a virtual environment (which is a good practice to manage dependencies and avoid conflicts), ensure you have activated it before running the above command. Sometimes, you might have multiple versions of Python installed on your machine. If you're not sure whether pip is installing the package for the correct version of Python that you're using, try using `pip3` instead, or be even more specific with something like `pip3.8` (for Python 3.8): ```shell pip3 install pytorch-lightning ``` Alternatively, if you are using conda environment, you can install PyTorch Lightning using conda as follows: ```shell conda install -c conda-forge pytorch-lightning ``` If you encounter any errors during the installation, they could be due to several factors like outdated pip, permission issues, or incompatible Python versions. Make sure you have the latest version of pip by upgrading it: ```shell pip install --upgrade pip ``` Also, if you're installing the package globally and you encounter permission errors, you might need to add `sudo` before the command for macOS or Linux: ```shell sudo pip install pytorch-lightning ``` For Windows, you can open the command prompt as an administrator to achieve the same effect. However, it's generally advised to use a virtual environment to avoid such permissions issues and not to install packages globally. Please note that PyTorch Lightning requires Python 3.6 or higher. If you have an earlier version of Python, you'll need to upgrade your Python installation before using this library. After installation, you should be able to import PyTorch Lightning in your scripts with: ```python import pytorch_lightning as pl ``` If you are setting up a project, it’s a good practice to list your dependencies in a `requirements.txt` file or setup `environment.yaml` file for conda, which makes it easier to manage and share your environment setup.