To do the python-MD tutorials you have to open the .ipynb files in jupyter-notebook. Download the files by clicking "Clone or download" and then "Download zip". Extract the whole zip file.
If you don't have jupyter-notebook installed yet, go to https://www.continuum.io/downloads and install the latest Anaconda version with python3. Then start "Anaconda Navigator" and click on the jupyter notebook launch button. Navigate to the downloaded and extracted files and open the respective .ipynb file.