epub books mainly r for smart phones and pads, or they call it tablets now. but what if you don't have one? don't worry, you still can read them on you PC, just need to download a free software so you can read all those free ebooks!
visit this website: http://www.adobe.com/products/digitaleditions/
and follow the instructions to install ADOBE digital editions to your PC. (you may need to sign up if you are not a adobe member....I've tried it...to sign up as a member is free and quick)
now you r done and have a local app. of adobe digital editions on your PC. just add whatever epub books u have into your library and start to read........all free.
here are some screen shots....surely I'm using a chinese version....you can choose an english one. it's all under your control!