I’ve searched, but can’t find a guide. Any help appreciated.
There isn’t really much to guide trough.
You can find list of features in the app info here and watch a short video review for the app linked there.
Most options are available either from the top right menu or from the entries menu (3 dots on Android or long tap on iOS).
There are few articles under this app category covering some specific features and if you have other questions, please don’t hesitate to ask.