Where can I change a songs lyrics?

I'm trying to make a video for a friend. And in order for it the video to be complete I need to put the song I made as its highlight. I changed the lyrics of her favorite song (pokerface by lady gaga) to match the video. So, i'm asking where, err what site can I use to change the songs lyrics? I just want to change the lyrics and not the complete song. Thank you.

You can't selectively remove the vocal from a sound recording and replace it. You might find a karaoke background for the song and sing the new lyrics yourself.