Once you have downloaded your file, if you need additional help connecting it with your device or app, follow the appropriate instructions below. It also might be helpful to visit your specific e-reader's website for more specific step-by-step instructions.

Instructions for loading to your e-reader

For Kindle App on iPhone

Download the Kindle file on your phone.
You should be prompted to "Open in Kindle"
Voila! Enjoy your e-book

For Kindle App on Android

Download the Kindle file on your phone.
Email the file to your individual Kindle email address which can be found in the settings of your app. You must ensure that the email address you send the file from is an approved safe sender to your device. You can do this under the "Personal Document Settings" section on the "Manage My Content and Devices Page" in Amazon.
In your app, Sync your content
Voila! Enjoy your e-book!

For Older Kindles

Download the Kindle file on your computer.
Email the file to your individual Kindle email address which can be found in the settings of your app. You must ensure that the email address you send the file from is an approved safe sender to your device. You can do this on the "Manage My Content and Devices Page" in Amazon
On your device, Sync your content
Voila! Enjoy your e-book!

For Other e-readers

Download the iBooks/Nook/etc. file on your computer or phone.
Open the e-reader app (such as iBooks) on your device.
On your device, Sync your content
Voila! Enjoy your e-book!

It might be more helpful to visit your e-reader's website for more specific step-by-step instructions.

Helpful notes:
".mobi" file types are used exclusively for Kindle
".epub" files are for every other type of e-readers including iBooks and Play Books.