how do I update my karaoke file so others can share?

mIRC doesn't have any such feature...

There's a list of songs that I downloaded how do I share these songs there's a way to update my karaoke file I did it once but don't remember.

Perhaps you used a script? mIRC has a built in File Server, but it's quite crude. You can get help with it on /help /fserve and access it through options at ALT+O > DCC > Fserve.

However, please note, mIRC is not specifically a file trading program.

Regards,