First off welcome to the site. You need to go up to Roll Call and give us an intro to yourself so we know what kind of equipment and experience you have.
You say you have a shoulder so I'm going to assume you have a boston butt.
Have you ever smoked anything before?
Now we need to know what kind of smoker you have.
What are you using for fuel?
Is this for pulled pork sandwiches?
There are aany number of different rub recipes so you're just gonna have to searcharound and find one that sounds good to you. Most uf us rub the butt the night before and let it rest in the fridge overnight in some sort of plastic wrap or container.
Early the next day it will go into the smoker and slow cook at a temp between 225 to 240 or so degrees until the internal temp of the meat reaches around 165. At this stage most folks wrap the butt in foil or put it in a foil pan and cover with foil and then continue smokin until the internal temp is 205 or the bone readily comes out of the meat. Drain off and reserve the juices, let the butt rest covered for about a half hour and then pull.
Allow up to 12 hours for the cooking process. Some butts cook a little faster than others and some seem to take all day. There's a point in there where the meat will stall at 140 or 145 degrees. It will appear that the temp is not rising and you will have the urge to crank up your heat. Just leave it alone. This is the point where the connective tissues are converting that energy and breaking down.
Patience, patience and more patience will be the key to a successfull smoke good luck and do post up some pics, we love q-view here..