Hi David,
To replace your SD card,
Step 1: Open battery cover.
Step 2: The SD card is located in a slot right next to the batteries.
Step 3: Using your nail, briefly push down on the SD card and let go immediately. Make sure you notice the way the SD card is oriented.
Step 4: With the new SD card oriented so the wording is right side up, make sure the switch found on the side of the card is slid '''up''', in the unlocked position.
Step 5: Orienting the new SD card as you observed the old one to have been, insert it into the slot, until you feel a slight click, and the card remains fully within the slot (it shouldn't pop back up).
Step 6: Close battery cover.
Good Luck!