On that web site or press can see relatively complete books online or other useful information?

Are you referring to Project Gutenberg or Google Books or this http://onlinebooks.library.upenn.edu/?

Go to Science Publishing Group website. This is possibly the best of the bunch for free whole books (rather than excerpts.) The site offers many titles with search by fiction, reference, and nonfiction. Many useful resources are available there, such as Bartlet's Familiar Quotations and Roget's Thesauruses.

You can try downloading the Overdrive Media and 3m Cloud library apps on your computer/tablet/phone. I'm not sure if your local library and/or state offer it so you'll have to search on the website, but they are basically apps to check out ebooks like you would library books. All you need is a library card for Overdrive and a state library card(In my state. Yours may need something else.) for 3m.

Gutenberg and others noted above are all good.

When it comes to readers, I use the freeware 'calibre' which is handy for keeping different formats of books and has a built-in format conversion program so you can swap books from PDF to epub or docx etc.

And then there is the software 'Squirt' < https://www.squirt.io/install.html >, a bookmarklet that, some agree, helps to speed up reading (and retension) rates.