You will need to get a public library account and card to access free ebooks. Visit your local branch library to apply for a library card.
There are so many sites offering free e-books! You can use any good search engine and search for "free ebooks" and find more links than you can follow. However, there is a risk that some sites may have malware. If it looks too good to be true, it probably is. Try some of these sites listed below.