Sylvia, what exactly happens when you try to upload your book? What is the error message? How far does the upload proceed?
The most common reason for not being able to order a book are wrong security settings. Check, that your apple ID password is compliant with Apple's security rules, at least 8 charachters, one upper case letter, one number, and the answers to your security questions need at least to be 6 characters long, see Apple ID: Tips for protecting the security of your account
If your security setting do not meet these standards, change them from this page:http://www.apple.com/support/appleid/