I want to make a 45-min 'fluid' mix for my aqua fit class

I'm an aqua fit instructor and have created a few playlists for my

45-minute classes in iTunes that I've uploaded to my iPod Nano. It's not fluid.

I want to sync the beats per minute of each song and remove the

silences between tracks.

I'm assuming I can do this in GarageBand 10.1, but I have no idea how.

Is there a simple, straight-forward way for a beginner to accomplish this?

Thank you in advance for any help you're willing to give.