First off, I would appreciate it if you would limit the attitude given to those attempting to help you out with the extremely limited information you are offering. People are spending their limited time to assist in you in something that is typically quite trivial. It doesn't do you good to respond to that consideration with negativity.
Secondly @neil9000 is very much correct. There are no additional steps needed to get good roms to work in that core. I would delete the core as well as any files/folders you added when following the libetro docs and then redownload the core through the RetroArch UI/Menus. I personally would install another instance of RetroArch to a different folder and try there, verify if it works correctly, then if it does update your live install to match.