Two sorts of smoking - hot smoking and cold smoking. Hot smoking cooks the fish, cold smoking doesn't.
For hot smoking, you can use a small purpose made hot smoker over a heat source, or a barbecue with a lid. I use the chiminea thing we have, I wrap the fish in chickenwire and dangle it down the chimney. Takes about 20 mins. I usually briefly brine the fish first, but it isn't essential.
The chiminea is this sort of thing:
For cold smoking, you need your fish far enough away from the heat source that the smoke has cooled down by the time it hits the food. You want to give the fish a proper brining first, then into the smoker. You want to leave it in there for hours.
My cold smoker: