To automate the creation of a new page in OneNote when a new database item is created in Notion, you can use Zapier to connect these two apps. You start by creating a new Zap and selecting Notion as your trigger app. This triggers an authentication process with Zapier to secure the connection. Once authenticated, you set up the trigger by selecting the specific database item type and pulling in example data for testing. Next, you create a new action in OneNote, authenticating it with Zapier and assigning the relevant data fields from Notion's trigger app. Finally, you test and review your setup to ensure everything is working as expected, allowing you to turn on the automation and create new pages in OneNote whenever a new database item is created in Notion.