General familiarity with the Drupal platform is a baseline requirement for anyone working on the site. We suggest reading through the following user guide to Drupal 8:
{% embed url="https://www.drupal.org/docs/user_guide/en/index.html" %}
Additionally, Acquia's free training program Acquia Academy offers a series of Youtube video tutorials which can be found here, including a Drupal 8 Beginner's Course:
{% embed url="https://www.youtube.com/user/AcquiaTV/playlists" %}