With the display facing down and the volume and power buttons located in the lower-left, open the SIM/SD card cover door (located in the lower-right).
Utilizing the notch, lift then rotate the door cover away from the slot.
With the gold contacts facing down and the notch in the upper-left, insert the SIM card as shown.
The SIM card slot is the bottom slot. The SD card slot is the top slot.
Press in on the card in until it slides into place.