Hi,

You can download book online from various website in the aneroid phone. Some of the website from which you can download book free are Google play book, project Gutenberg, Amazon, Library Genesis, Internet Archive, Google Scholar, Digital Public Library of America, BookBoon.

To download book visit the particular website from which you want to download. Search your prefered book,  tap to download option. Then the file will be downloaded.

Hope this information will help you