Open https://notebooklm.google.com (Google account). Create a notebook. Upload one short public PDF or paste a short public article (not private work files). Ask: 'What are the 3 main points in my sources?' Completion: you got an answer that cites your source — or you noted if the product asked for sign-in and stopped cleanly.
How-to · INF · INF.1
NotebookLM as a sidekick (Tim priority)
NotebookLM is strongest when answers stay grounded in sources you gave it — not free-floating invention.
Worked example
NotebookLM (Gemini Notebook) is a sidekick worth mastering: grounded answers from sources you upload — less free-form hallucination when the notebook is set up right. Like a knowledge base you set the knowledge for.