Power on the unit and then insert the SD card ...

There should be a green popup asking if you want to load Nav data ...

Press the 4way cursor right to select Yes ...

If there is no green popup - something is amiss with the data on the card ...

Where did you get the waypoints ...??
Did you upload the waypoints to the SD card from Humminbird PC ...??
Did you export these waypoints from a different HB unit to the SD card ...??

Rickie