Sampling How To with GarageBand  (some examples to get you started)

http://www.ehow.com/how_7659720_sample-garage-band.html

https://www.youtube.com/watch?v=ajReyyN3aSs

https://www.youtube.com/watch?v=py-G3lxz4Ow

Sampling How To with Audacity (some examples to get you started)

http://www.ehow.com/how_8492258_sample-audacity.html

https://www.youtube.com/watch?v=Vlbq4n1-ucc

https://www.youtube.com/watch?v=5Ukqok2TWmc