An internal USB port does not use a traditional USB connector. You cannot plug a big USB cable into it. It is a small connector with pins (like the audio connector on a soundcard.) If you look at that picture again, you would plug the black connector on the pins of the "internal USB port" on the card and install that plate in a slot on the back of the machine. Hope I'm making sense here.
Edit
Actually, as I look at the picture again, it DOES look like an actual USB port. Sorry pmark. Ya got me on this one. Maybe this is for a front panel connection????