You may have to download an eBook reader to your device. Which one, would depend on if you're using an iPhone (iOS) , an Android, or reading it off your PC; and also whether you want the Amazon Kindle edition or an ePub edition. All the following are free downloads:
Rats in the Cellar is free Smashwords.com but costs just a little bit at Amazon Kindle. You can still get it free as a Kindle copy by sending it as an email attachment to your Kindle email. You just need to know your Kindle username, then your Kindle email would be something like: <Amazon username>@kindle.com