Once you enter the iBooks Store, the browsing and searching experience is very similar to using the iTunes Store. In this case, you can search for the author or title you want in the top-right corner search box.
To browse books, either tap the icons on the main page of the store or tap the "Categories" menu item in the top left corner. This drops down a menu with all of the iBooks store's categories in it. Tap the category you're looking for to see books in that genre.
