OK I downloaded Adobe Digital Editions onto my Mac and then bought a book (or a few) from eBook stores.
Then I downloaded OverDrive onto my iPhone.
So how do I get the books from Adobe Digital onto OverDrive?
I can seem to drag into iStore as they are in a format .acxm and there is no synching facility between Adobe Digital and OverDrive
I'd suggest using Bluefire Reader instead. (You could then transfer the ePubs into Bluefire Reader using iTunes).