Well, it's fairly certain that you would not do it with Pages, an application that runs only on the Mac OS and iOS.
You might try asking you question here: Creating Books for iBookstore
How do i create an ePub file for ibook on Windows platform?
Adobe Indesign can do this. I'm sure a simple google search would find various Windows apps.
You cannot submit books directly to Apple using a Windows machine, you would have to use an Aggregator like Smashwords. So you might want to see what format the Aggregator prefers.