I downloaded the iBooks app and then downloaded a book I thought I'd like. I opened it to the first page, then wanted to go back to the main screen, but there's no option to close the book other than closing the entire app! The only thing it responds to is to turn the pages by swiping your finger. Double-tapping just maximizes it. There's no "return," or "search," or anything on the screen. Clearly I'm missing something.