Open Print-ready from the Home screen (or use its own page link).
Tap Choose file and select your PDF from the phone or computer.
Choose 2 pages per sheet.
Set the Margin (None, Small or Normal). Tick Page numbers or Remove blank pages if you need them.
Tap the big purple Start button and wait a few seconds.
When you see Done!, tap Download. The new file is saved on your phone or computer.