It’s a pretty simple process to add ebooks to your ereader. The file extension for an iPad and a Nook is .epub. The file extension for a Kindle is .mobi, although it is possible for a Kindle to convert an .epub file to a .mobi. Mostly it’s a drag and drop process. I’ve put links here for you that illustrate the process.
Instructions for iPad and iPhone:
Instructions for Kindle:
Instructions for Nook:
With computers, there’s generally more than one way to accomplish a task. I’ve found these to be efficient.