How to get my micro SD card to work when put in my eclipse fit clip plus

Don't have one but reading about it says mico sd card expands the memory up to 16gig. That means it has 8 gig fixed memory and additional with the card. Insert the micro card in the unit and try adding songs with the eclipse connected to the PC instead of putting them directly on the card. When it gets past 8gig the rest should go to the extended memory no?