The files with the .ipynb suffix are jupyter notebooks.
Jupyter can be installed for free an all platforms.
In case you don't want to install jupyter, html versions of the files are provided.
You can open those using your favourite internet browser.


Finally, the tutorials can also be found online:


    All python3 tutorials:
        https://obswww.unige.ch/doc/rst/Tutorials/python3.html

    Numpy:
        https://obswww.unige.ch/doc/Notebook/Numpy3.html

    Scipy:
        https://obswww.unige.ch/doc/Notebook/scipy3.html

    Matplotlib:
        https://obswww.unige.ch/doc/Notebook/matplotlib3.html

    pNbody:
        https://obswww.unige.ch/doc/Notebook/pNbody3.html


There also is a UNIX/linux tutorial availbale, though in French:

    https://obswww.unige.ch/doc/rst/Tutorials/unix.html


A good, simple introduction to bash can also be found here:

    https://linuxconfig.org/bash-scripting-tutorial-for-beginners