like tiraq says, look about half an inch in, at the top and bottom of the recoil pad, where it rests against your shoulder. Take your thumbs and use them to tug the pad from the center. It should show you the holes (there is a very easy analogy for this, but I am trying to keep it clean).
If its synthetics, then IIRC they are all Phillips screw drivers, #2 I think. Once you find that little hole, push a screwdriver coated in oil into them. You should feel the tip hitting the end of the metal on the screw. Them the butt pad, and a plastic plate it is attached to come off. After that its the big azz screw driver (I used to use a modified drag Link Socket and 1/2inch wrench), and pop the butt off the gun.