Incorporate design in a Drupal theme

I have a deisgn made by a designer. He also created the html/css which looks realy nice.

Now I have to incorporate this in Drupal, such that the Drupel mechanisms (menu’s, breadcrumb, content stored in nodes etc.) are incorporated. How do I start with this? Should I take a standard Drupal theme? Do I put Drupal theme parts in the design or do I put design parts in the Drupal theme? How should I approach this? Any directions are welcome!

I use Drupal 8.

Drupal version: