Though most themes include a search bar in the top navigation, you might want to include a search bar in your table of contents, as well.
To add a search bar to the top of your table of contents:
- Go to Settings > Basic.
- In the Table of contents section, check the box next to "Add a search bar to the top of the table of contents".
- Save. You should now see the search bar at the top of your TOC.