What procedure do I follow to open/unpack and read a book that is downloaded in a .zip format? I found a place in settings where I could select extensions. I can see the download, but I get a message that says "cannot open the file. Need help. BTW. I did not know it was a .zip file when I downloaded it. And, I paid for it. So, I hope I can find a procedure or an app that can open it. I have a premium nextbook 7. This is the first problem I have run into with this great device. Thanks.