Import books or PDFs
If you have books that you didn’t get from the iBooks Store or PDFs that you want to open in iBooks, you can import them into iBooks.
In iBooks, choose File > Add to Library.
In the Open dialog, select the books or PDFs you want to import, then click Add.
If you have books in iTunes that you want to add to your iBooks library, you can also choose File > Move Books from iTunes.
Note: To see imported books and PDFs on all your devices, use iCloud for iBooks.