Buy one of these: https://www.amazon.com/Greenlee-09-03-54B-DVersiBIT-Combination-54-Inch/dp/B000FCGT12
You can stick this drill bit through the cutout for a wall plate, drill through the bottom wall plate & subfloor, then go to the basement & tie your cable to the drill bit and pull it back up through the floor.
>I don't even know how to do it
Oh, man, you need a Flexible drill bit.
With a 54" bit, this lets you drill through 3 studs (16" on center) from a single hole in the drywall. You've got to cut a hole every 5 feet or so, but if the hole in the drywall is cut properly, you can just install outlets if you don't want to patch it.