There are 2 ways to search a word within a book:
(1) Selecting a word or a string of words (by touching and holding it), you will then see a pop-up menu showing up. Scrolling horizontally to select the "Search" icon.
(2) Tapping on the center of your device’s display, selecting the “Search” icon at the top right corner. Typing a word or a string of words in the search box and then tapping on the search icon.
After search, you will see the list of pages where the words appear. Tapping on a particular page will bring you to that page and the words will be highlighted.