Welcome to the forums. Is it okay to wipe the memory card you inserted? -this action is irreversible and will delete the contents of your entire 64GB memory card.
If-so, go to the home screen, then search for "format." Choose "Storage and Access." Next choose "Format Media Card.". Give it up to a minute and you should be good.
If you haven't used a memory card in a mobile phone before, you can specify in the camera application to store your photos on the media card.