How do I save documents on my iPad mini?

You can open and save Word, Excel, Powerpoint and PDF document to free Quickoffice.

It depends on what sort of documents you are talking about and where they come from. Are you talking about documents created on the iPad or documents created on a PC/Mac that you want to transfer to the iPad? What type of documents? Word, or some other text format documents? Excel spreadsheets perhaps? Some other document type?