Looking for some help with Capti Narrator

iOS and iPadOS

Does anyone have any experience using Capti Voice Narrator? I would really appreciate a walk thrue of how to get the app to read my iBooks to me. I am wondering if the app can do this or only get content from the web. Its a really fantastic app. I'm of course missing something on my end.
Thanks and have a good week. A big thanks in advance for your help.