Let me say first of all that I'm a rank beginner with RB.

A friend sent me a mp3 file of him playing a guitar. I loaded it into RB and then recorded a couple of fiddle tracks to go along with it.

My friend then sent me a second mp3 containing a harmonica part. I can import it into RB, but can't - for the life of me - figure out how to slide it back and forth on the track in order to align it with the other tracks.