[Phlogiston]

There are no stupid questions here...
It might help to know exactly which radio we are talking about, a picture of the front and back might help if you don't know the model number, but in general in that time frame the antenna and ground were connected to clips on the chassis as seen below:

[Image: https://dl.dropboxusercontent.com/u/5462...ground.jpg]

The clip on the left is the insulated one (i.e. insulated from the chassis with the round wafer you see it sitting on.  The one on the right is connected directly to the chassis and is the ground.  So you clip that 20 foot long wire to the one on the left and it should pick up stations.  As Russ suggested, let us know if its working or not.  It would also be good to know if the fellow that you bought the radio from had it serviced recently.  If its still operating on the original electrolytic and paper capacitors it probably won't be working too much longer.  

Yes, and the last two sentences above are SO important that they bear repeating (though you can just read them again above).