Stanza automatically opens to the last book you were reading, if you previously closed Stanza while you were reading a book. To get back to the Library screen (or "main menu"):

1. Tap in the center of the screen to bring up the toolbars.
2. Tap the back button in the upper left corner until you see the screen that says "Library" at the top.

The toolbars that appear when you tap in the center while reading are very useful. The gear icon lets you change font, font size, font color, background color, line spacing, and many other features. The other icons let you search and jump from chapter to chapter.