Juan,
there are many ways to use a smoker you describe, however, i'll tell you how i would do it....(being a professional chef for 15 years)
first i would brine the meat cut i was gonna smoke. this will add additional moisture that the smoking process will evaporate. if you are using a whole unprocessed brisket, there typically is enough fat on it that you dont have to brine it unless you want to impart a subtile flavor. this is what i usually do. i use a ratio of 1/2 apple juice concentrate, and 1/2 water. i heat this untill almost boiling, and add whatever spices you like.....i use about 4 or 5 cloves of garlic, a cinnamom stick, a few whole peppercorns and some kosher or sea salt.
Pour this over the beef and let sit in cooler for at least 24 hours.
when ready to cook, take beef from brine and drain well.
your fire should be in the main pit of the grill.
when ready, you need to have the wood chips also ready. you can buy almost any wood flavor that you want at a good store like home depot. most everyone uses mesquite or hickory, which is fine but i go for the more exoctic flavors....you may need to look further for these....i would use maple or pecan wood chips for this....
soak the chips at least an hour in water before using...
place brined beef on smoker side of grill...no do not cover it or use foil.....this will impede the flavor of the wood from getting to the meat....
put the wet wood chips atop the hot coals, and close lid. make sure the air flow form the grill passes thru the smoker to engulf the beef....
the length of time it takes for the beef to be done will depend on the thickness of the cut.....brisket is usually about 4-inch thick and will smoke in about6 hours, give or take...
....
this same process can be used with almost any cut of meat or fowl or game meat.
hope this helps you
keith