Thanks Ben for pointing anderml in the right direction.
Hi anderml, after you put in the SD card, you must press the LOGGING: button in the main display. The button should turn green. After that, every time the meter takes a reading it should be saved to the SD card as a line in a CSV file. When you disconnect from the meter it will continue sampling roughly once a second, you should see the led flash every time it wakes up and writes to the card.
I hope this helps, please let us know if you are still stuck. Best