Application Loader can't recognize my username
I'm on Barnes & Noble trying to download a .epub book. The .epub goes to my Download file and when I click it Application Loader pops up asking for my Apple ID and password. It says it cannot find a registered user with my user name.
I don't know why it even pops up. It says its purpose is to help me prepare my apps for sale on the App Store. I just want to open the .epub.
Please help me.
iMac, Mac OS X (10.7.3), Safari 5.1.2 iPhoto 8.1.2 Time Caps