I've been trying to figure out how to get eBooks without success. My goal is to get my library on my iPad. Can someone outline the steps/apps to do that?

First I downloaded Adobe Digital Editions to my Mac and activated it on my Adobe account. Next I downloaded TestSuccessful.acsm and double-clicked on it. ADE starts and gives this very helpful message: E_LIC_ALREADY_FULFILLED_BY_ANOTHER_USER

I am reluctant to purchase anything until I see what happens next. Does a pdf eventually get downloaded? If so, I know that can be read on the iPad.

Thanks for any help.