There are 2 ways to jump to different sections within a book:
(1) While reading, you can access table of contents by tapping on the center of your device’s display, selecting “Go to” icon (the icon with 3 vertical dots and 3 lines), then tapping on “Contents”.
(2) At bookshelf, you can access table of contents by
(i) doing a long press against a book cover at grib view, selecting "Detail" from the pop-up menu and then selecting “Contents”;
(ii) swiping the list from right to left, selecting “Detail” at list View, then selecting “Contents”;