[foxfish]

Crumbs I must of written a 10000 word on smokers!
The easy way to start would be - Make a BBQ in a oven tray, set it on the ground. Get a metal tin (biscuit or quality street type) drill a few small holes in the tin, top & bottom. Get some oak sawdust, dampen the dust & place in tin, put on lid & place on top of BBQ. You will need to contain the smoke that is produced - maybe an old drum or dustbin, you need some way of suspending you fish in the bin. Place bin over the BBQ & keep your fingers crossed!!
Lot of variables can happen, it is not a precised science, ambient temperature, flare ups, fire goes out etc etc.
You need to brine your fish first, try 1 x cup of salt & 1/2 cup of sugar in 2lts water for 45mins? Again trail & error because every fish requires different attention. However brine you must - smoke & salt go together like gin & tonic!
This method is termed as hot smoked where the product is cooked as well as smoked. Try this first then move on to cold smoking - cold smoking is more involved but produces a superior end product.
I refuse to explain cold smoking to any one who has not carried out their apprenticeship with hot smoking first - good luck.