[Q] How to install cereberus.apk as a system file?

Hi
I have a question because I don't know how to install cereberus.apk as a system file.
I have single .apk file but in system\app I have some folders with apk files inside.

Do I need to make folder for my apk file or only copy this and change permissions (644)?

And which is the best place for this apk:
*system\app
or
*data\app?

Thanks a lot