Place the inner pot into the cooker base and set the trivet that came with your IP in the bottom of the pot.
Pour the water into the pot and then place the potatoes on the trivet. Lock the lid into place, making sure the nozzle is in the sealing position.
Use the manual setting and set the timer for 15 minutes. Use the natural release method when the timer is up. When all the pressure is out of your pot, carefully remove the lid and allow your potatoes to cool a bit before you use them.
If your potatoes are really small, follow this technique exactly, but set the timer for 10 minutes instead of 15 minutes.