Replacing Gas Cap on my '66

[Ice Cream Guru]

...and I need a nudge. The cap came with a cable, which was great. And there's a screw with a nut also on the cable. I can't figure out how to install it - I thought it was going to come with the cable separate and I'd string it thru the old slot on the car at the filler and then through the cap...but it seems that the cable is already intact. I did get a screw out of the filler cap area thinking I'd be screwing that attached screw in, but of course you can't as it is because it won't turn since it's threaded on the cable. I must be overlooking something simple but I don't know what it is and can't find any video or online help or hints. Can anyone point me in the right direction? Thanks!