Urgent - how to upload ebook to iTunes and read in ibooks??

using the most update os and iOS

in iTunes - did not see anything for books unless plugin with a device

but the problem is - books are not bought in iTunes

Format - PDF, mobi etc

Can I read in ibooks app?

BIG PROBLEM: how to make all the books readable in ALL DEVICES, etc, iPhone, iPad and MBA by using ibooks app

THANKS C-hing

quick trip to the Apple Support page answers your questions:

http://support.apple.com/kb/ht4059

by the way, the backlit iDevices are not the best for reading. In that respect, the Kindle blows it away regarding eye-comfort.