If you mean taking a screenshot of your ipod touch. If you press the home button, and power button at the same time. It should take a picture of the screen, and save it to your photos app (the one that is part of ios). Make sure you just tap and release both buttons, do not hold them down.
Late 2012 Mac Mini, 2.3 i7, 16gb ram, 250gb Samsung 840 SSD.