OK, sorry to sound so redundant, but the SD card goes next to the HDMI port, right? If that's right, where would the flash drive go? Yes, I thought about not getting the 256 because I don't plan on storing anything else. If I decide to, I guess I could get another SD card.
OK, so now I am so confused I want to forget it. Which device goes into the large slot next to my HDMI slot? That's what I want to buy because it's the onyx freed up slot at all times.
This is the SD card to which joemike linked. ("This" is a link.)
And bear in mind that because of the size of your internal drive, you don't need 256 GB. 128 GB will suffice (unless you want to use the card for data storage as well as backup).