I'm no expert but pork ribs are pretty easy. I've bought them at a lot of places but Kroger's has best price for quality of meat you get on them. You can usually catch them on sale for $2.99 lb for the back loin ribs (baby backs) and they have fairly large portion of loin meat on the end of the rack. Don't worry about fat or shiny tendons on them, that will all render down and help tenderize and help moisten the meat over the cooking time. I pick over them or get the meat dept guys to go in the back and get at least 4 - 4.50 lb slabs. For the baby backs those will have a lot of meat on them and run you about $12-$13 a slab. These aren't the slabs you typically get at Damon's or Famous Dave's, these will each serve 2-3 guys.
PREP - rinse them with water and pat dry with paper towel. Then remove the membrane on the back/underneath the ribs. There are plenty of you tube videos to show you how if you don't know. The easiest way is to use a spoon or butter knife and start at the tip end and take the spoon/knife and pry the membrane loose from the back side of the rib. Once you get it loose use a paper towel to grip it and rip it all the way down the rack until it's off. You need to remove membrane because no seasoning or smoke will penetrate it and if you leave it on it ends up tasting like like a crunchy paper bag.
RUB - rub the rack down with either mustard or olive oil. This is just a base for the dry spice rub to stick to and it helps tenderize the meat. I'll leave it to someone else to chime in with dry rub recipes. I usually make a rub heavily based in sweet Hungarian paprika as the main ingredient. Or for your first time just use pre-made store bought rubs like Stubb's, Weber's, McCormick's, etc until you find what flavor profile you like. Once you find one just mirror the ingredients until it taste good to you. Unfortunately most brand name rubs give a few ingredients and then list the word "spices" which doesn't let you know exactly what they have in it, but it gives you a starting point. After you get the dry rub on I recommend letting them sit in the fridge for at least 8 hours to let the flavors permeate the meat. So you might want to do your prep the night before or the morning of.
COOK - Get your heat to 200-225. I recommend getting a digital thermometer because temperature is important and the thermometers on most grills and smokers is useless. I have a 2 probe thermometer (1 for air temp and 1 for meat temp). With ribs the meat temp is not that important because they're technically done after the first hour but they don't get tender enough to eat for at least 4 hours on the smoker. I usually go 4-5 hours or 6-8 beers ;)
There's a bunch of different methods for cooking ribs. NEVER, EVER pre cook ribs in the oven or boil them. That's smokin' blasphemy. For the first time I would recommend cooking them unwrapped. Always cook them on indirect heat. I'm not sure what kind of smoker you have. If it's an offset box then everything is indirect. If it's heat on the bottom then you need to get the fire to one side and put your ribs on the other. Again not knowing the layout of your cooking surface you can either lay them flat, meat side up or buy a rib rack and stack them sideways. Either way will work fine.
SMOKE - Never use green wood. Also use chunks or logs and not "chips" as chips tend to burn up quick. If I use chips I mainly do it for finishing in the last 30-15 minutes. The wood does NOT need to be soaked or wet but does need to be seasoned (aged). You can use smoke any time but you want to avoid thick heavy white smoke. Since your cooking time is going to be at least 4 hours a little goes a long way. You can use smoke boxes, wrap wood chunks in foil or just throw logs directly on the fire. All will work fine to flavor the meat.
Once you get the smoker up to temp, put the ribs on. Once they start cooking go mow the grass, drink some beer, wash your truck, walk the dog, drink some beer, ect until 3 - 3.5 hours have passed. Then you can spray them with apple juice if you want. Close the lid and let them go another 30 min and then mop them with whatever sauce you like. Close the lid for 30 more then they should be ready. You don't want to sauce them until the last 45-30 min so the sauce doesn't burn.
Here's some of mine in the pics below. You'll know when they are ready to eat when you see the meat shrink back from the bones. Also, there are a bunch of cooking methods like wrapping in foil, using foil pans and using water that you can try that are listed at the link below. Good luck and let us know how it goes.
http://amazingribs.com/table_of_contents.html