The Jupyter Notebook file browser is where a new .ipynb document starts before code, notes, and outputs are added. Creating the notebook from the browser keeps the file in the current server folder and connects it to one of the kernels registered with that server.
Notebook 7 uses a New menu in the file browser for notebooks, files, folders, terminals, and consoles. Selecting Python 3 (ipykernel) creates a blank notebook, opens it in a browser tab, and starts a Python kernel for the first code cell.
The default Untitled name is safe for a quick scratch file, but renaming it immediately avoids duplicate Untitled1 files and makes the file easier to find later. The saved state to check is the renamed .ipynb file listed in the same file browser folder.
Use File → Open… from an existing notebook if the file browser is not already open.

The new notebook opens in a browser tab and starts with an empty Code cell.
Keep the .ipynb extension so Jupyter keeps treating the file as a notebook.

