Two nice iMaschine videos from the realms of Native Instruments
This tutorial explains how to record short one-shot samples to the pads,
and how to record a longer vocal loop using the built-in audio recorder
This tutorial explains the basics of working with iMaschine, including
navigation within the app, loading sounds, adjusting the tempo, and
programming a simple beat.
More info about iMaschine: http://www.native-instruments.com/imaschine