Launch the App

On the footer of the App, click on "More"
Go to "Create Book"
You will be redirected to the Okadabooks account on web
Sign in and click on "Publish" on the left-side of the site.
Click on "create your story", fill in the required details.
Scroll down to the bottom, you would see "upload ePub" or "create ePub".
Click on "upload ePub" to upload your ePub file.