To help you stay organized, you can create subpages in OneNote on your iPad or iPhone. You'll need to have a least two pages in the section before you can make one a subpage.
In the list of pages, tap Edit.
Tap the page you'd like to set as a subpage, and then tap the right indent icon at the bottom of the page list.
The page will become indented, and will be a subpage of the page above.
Tap Done when you're finished editing the pages.