What do you call an app that lets people read books you uploaded?

I want to create an ebook type app, that let's people read books which I will upload. They won't be able to download them, just view them. Does anyone know of a similar app I can look at as an example or search a Youtube video how to create such an app.

I downloaded Android Studio and it's confusing the hell out of me. I found an open source app on GitHub called koreader. I would like to use this in Android studio and then edit it.