If they came with a hammer they are probably Dayton or Zenith wire wheels. They should have come with adapter plates that bolt on to your car where your wheels would normally go. Next you place the wheel and tire (already mounted and balanced of course ) and slide the center of the wheel over the adapter. Next take the knock-off ( spinner, center nut, etc. ) and thread it onto the adapter. These threads may be reverse thread if I remember correctly. Try righty-tighty first if that doesn't work try to reverse the thread. Once you have it hand tight, lower the car from the jack or whatever lift and use the hammer to tighten the thread some more. It should be a lead hammer to minimize any damage to the knock off. Try not to hit the dish of the wheels while you're doing this. This is what holds the wheels to your car!
As you drive and the wheels spin, it should further tighten them on. Hope this helps!