CIA is a container, it's not something you convert. That being said, you can use ctrtool to extract it into a cxi, and then from there, get the exefs, romfs, and exheader from the cxi. Or grab Asia81's hackpack maybe, if you'd prefer batch scripts that walk you through it.
so first i covert them to cxi then extract and then I canuse pk3ds right? I'm asking because i'm unable to dump my pokemon game using braindump - my game is a installed cia pokemen game