How to choose my core for current rom in Onion? ( Papriun)

[Iga44]

Hello.
I have modified core for paprium rom.
So what i need to do to run rom by my core in onion os?

Ok, when we press Y in roms menu we get menu with list where could choose a core for rom. But what need to do to my core appeared in this list of cores?
There are cores: https://dropmefiles.com/3vscs

Put it ( genesis_plus_gx_pap_libretro.info and genesis_plus_gx_pap_libretro.so ) in F:\RetroArch.retroarch\cores