To create a new collection, go to the dashboard and click the +Add button below the left menu. Click Collection.

Name your collection under Collection Title and select a Visibility option.

Public collections are visible to anyone with the URL. Organization collections will be displayed on the dashboard for all users within your organization. Private collections will only be visible to you and invited collaborators. For more detailed information on inviting collaborators, see Collaboration. 

Click Continue to start building your collection.