Usage patterns
〈事〉に見出しをつけるto give something a heading/headline
I gave the article an easy-to-understand headline.
見出しで〈物〉を探すto look something up by its index entry/heading
I looked for the item I needed using the index entries.
見出しに〈事〉と書くto write something as the heading
I wrote 'New Product Launch' as the headline.