Tagging a page would be helpful in quickly sorting and looking for a specific info inside a notebook. Just tap on the gear icon on your Notebook toolbar to go to your Notebook settings to tag a page. After typing, press 'enter' to save a tag.
To filter tagged pages, tap on the Double Page (Finder) icon on your Notebook toolbar then tap Filter to select tags.
You can also filter text you have typed on pages and imported PDFs. Do take note though that handwritten notes and imported PDF text cannot be searched and filtered within Noteshelf.