Section breaks
When you are restricted as to styles, you can change margins, page size, or orientation from this point forward or for selected text. This inserts a section break automatically. For selected text, it will add two section breaks.
To do more, you can use the Page Layout dialog.
Headers/Footers
You can use the StyleRef field to change what appears in the same header/footer on different pages. Many people think they need a section break to do what the StyleRef field can handle.