The app is not difficult to understand. However, here are some instructions for getting among with the app.
Allow permissions
Once the app started, it may (or may not) be that the app is asking you for some permissions. Allow them, they are needed for the functionality.
If you have doubts, have a look at Permissions to have an explanation for the usage.
Changing app's language
Qwotable is available in English, French and German. The app's language is the phone's default language. However, it may appear that you want to use another language.
Go to settings, click on "Languages" and set the app's language to your preferred language.