Greeting and welcome to the forums,
I have a brinkman vertical charcoal smoker like you described and have done several pork butts ribs and whole chicken (not at the same time mind you)
There are several things you are going to want to do first before you put and meat in the smoker.
1. take the factory temp gauge and throw it away.... these things are junk and are not reliable or even remotely accurate. the first time I used mine the temp guage kept jumping 100 degrees in a matter or seconds but my maverik stayed constant,
2. Take the charcoal pan and drill as many 1/4" holes into it as possible.... As they come from the factory there is no ware for the ash to go and will kill any heat or fire you might be lucky enough to keep going.
3.take the charcoal pan off the rack and have it sit about 1 inch off of the floor of the smoker (so the ash can fall to the floor). this is because ware the rack is is to high for the vent to work properly. if you can go buy a heavy duty colander (search google for mods on the smoker and there are several threads of what people did) as tha\ry are bigger and work very well.
4. Always add hot coals to it as you go, there is not enough charcoal to keep up the temp and start fresh charcoal.
5. use chips not chunks of wood, and only a little at a time
6. Time... like forluvofsmoke said things will take time and alot of attention for it to come out right. you alway want to go by internal temo of the meat not time... I have had butts of the same weight vary in smoke time by several hours.
7. be ready to babysit this thing... when I use mine I can not be away from it for more than 20-30 min at a time.
These smokers are very challanging to use and in my opinion not a good starter smoker.... I would honestly would say use it several times before using it for a event. Save time and any embarassment that might come (I know I have been there)
I hope that you do let this scare you away from smoking meat and hope you have fun learning.
also post pics we love to see "Q-view" of peoples smokes good or bad and remember