First, this is the content discussion forum. The web design forum is where you discuss web site construction software.
Second, a CMS is
Not an online version of Frontpage. If you thought dropping the code paypal walks you through confusing, you can't dream of what most CMS installs are like. Cutting and pasting the code PayPal gives you is one thing, learning PHP in order to write the code to accomplish the same thing is another.
One thing you might try is
ebook Pro, which seems like an ebook compatible CMS. (Although I'm not sure). That'll set you back $200.
But of course, this isn't the CMS software forum, it's the content discussion forum. You posted here not because you wanted software advice but advice about writing your ebook -- right?