Michel Wermelinger

Sorry for the delay in getting back. Can you give details in what led to this?

Are you using Jupyter locally (eg with Anaconda) or remotely (eg with Cocalc)? If the latter, then indeed you must upload your files so that you can work with them...

A name error means that the Python interpreter doesn't know what a name refers to. Either you've misspelled it or, in this case, you probably haven't run an earlier code...

The green button is on the main page (https://github.com/mwermelinger/Learn-to-code-for-data-analysis) of this repository, as shown in this screenshot: