We need username and password to log in to Django Admin page.
To first create a superuser, run:
$ python manage.py createsuperuser
Note: user information are stored in databases. When we first start up a new project, there is no user related database table existing. We have to run python manage.py migrate and apply all models migrations for the built-in apps, including the django.contrib.auth app.
To manage model migrations, see [[Create a Model in Django app and manage migrations]].
To change user password:
$ python manage.py changepassword <username>