On the Home screen, tap one of the 5 big cards: Scan with Camera, Sign a PDF, Password Protect, PDF Converter or Extract Text (OCR).
Tap Choose files and select all the files you need (you can select several at once).
Choose how to make the PDF: One PDF (all files joined) or One PDF per file. You can pick Word (.docx), Excel, PowerPoint, text, web page or pictures.
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.