Read this: https://zero-to-jupyterhub.readthedocs.io/en/latest/ https://zero-to-jupyterhub.readthedocs.io/en/latest/ then see the "Customization Guide" section

Read this: https://zero-to-jupyterhub.readthedocs.io/en/latest/ https://zero-to-jupyterhub.readthedocs.io/en/latest/ then see the "Customization Guide" section has a instruction on how to setup lab by default.