If your door is rubbing, or refusing to open or shut, tighten the hinge screws first, then try a grater plane to plane down areas that are rubbing. If this is not enough to fix the problem, corrective surgery must be conducted. Not to fear. Door frames are fairly simple. The frame is made up of two pairs of vertical studs, while the top or header is typically a double two-by-four running horizontally. The jamb, which is what you will be adjusting, is made up of three pieces of one-by-six or one-by-eight, depending on the framing of your walls.
Take the door from its hinges by removing the hinge pins. Tap a small screwdriver up through the hinge from the bottom with a hammer to release the pins. Set the door aside.
Remove the casing from your door frame with a flat pry bar and hammer. Tap the bar under the lower corner and pry the trim away from the wall. Move up the wall and work the pry bar under the casing and pry away from the wall as you go until the nails are all loose. Work up both sides and the across the top of the door on both faces of the frame.
Check the side jambs for plumb, using a level. Start on the hinge side of the door, as this is the most likely problem. Set the level against the jamb and adjust the level by tilting it out at the top or bottom to get the bubble in the center of the middle lines. If you have to tilt the level out at the top, this means you need to adjust the bottom of this jamb outwards; if you have to tilt the level out at the bottom, you need to adjust the bottom of this jamb inward.
Remove the shims behind the hinge side jamb with a hammer and chisel to correct a jamb that is tilted out. Tap the bottom of the jamb out from the center of the door with the level flat against the jamb until the bubble is lined up in the center. Add shims as needed to maintain the space that now exists between the back of the jamb and the inside stud. Nail through the jamb and shims to hold them in place.
Pry the hinge side jamb away from the inside stud to correct a jamb that is tilted in. Place the level flat against the jamb and pry the jamb away from the stud until the bubble lines up in the center. Add whatever shims are needed to hold the jamb in this position. Nail through jamb and shims into the inside stud.
Replace the door and test after adjusting the hinge side jamb. If the knob side jamb is out of line, adjust it in the same manner, moving the bottom of the jamb in or out to correct the problem. Test and readjust until your door operates smoothly.
Replace the casing. Pull the nails through from the back of the casing with locking pliers to avoid marks in the face of the casing. Nail the casing back to the edge of the doorjambs. Fill nail holes with painter's caulk or wood filler.