You can use Adobe Digital Editions to add EPUB and PDF books to your eReader, as well as books that are protected by Adobe Digital Rights Management (DRM).

To add an EPUB or PDF book to your eReader:
Connect your eReader to your computer using the included USB cable.
Tap Connect on your eReader.
On your computer:
Go to the folder where your eBook is saved.
Right-click the book file and click Open With.
Click Adobe Digital Editions. Adobe Digital Editions should start automatically, add the book to its library, and open the book.
In Adobe Digital Editions, click the Library icon.
Select your new book and drag it to the Kobo eReader bookshelf (listed on the left side under Bookshelves).

To add a DRM book to your eReader:
Connect your eReader to your computer using the included USB cable.
Tap Connect on your eReader.
On your computer:
Go to the folder where you downloaded your book's .acsm file.
Double-click the .acsm file. Adobe Digital Editions should launch and automatically download your book and open it.
In Adobe Digital Editions:
a.) Click the library icon in the upper left of the window.
b.) Drag your new book to the Kobo eReader Bookshelf.

Note: Books that are protected by DRM have an .acsm file extension. This is a license for your book. You must be connected to the Internet when you open this file so that Adobe Digital Editions can verify the license and download the rest of the book.