Hello,

Downloading the eBook of a certain books comes with a limitation for that you have to check whether the website that has your concerned eBook allows downloads.

If it does, search for 'Save PDF' or 'Download here' or anything that related to downloading, then click on that to save them. Usually it opens in a browser, if so click the downward arrow on the bottom of the page that directs you to he downloads there you can save the Ebook pdf.

In some cases, the concerned site only allow the people to read and not allow them to download one in such cases, you have to use the reader app(offline reading options).

Hope this helps. Happy Reading.