I am a complete beginner to Python/Django, but I want to dive right in and start experimenting. Thus I was following this guide on installing Python/Django http://devcenter.
It has to do with the PATH:
Put this in the .bash_profiel and the source it (for mac users only): (change the location with the location of your installed python libraries)
PATH="/Library/Frameworks/Python.framework/Versions/3.6/bin:${PATH}" export PATH