Do not do this on the street - call an ambulance. This should only be attempted when rescue is impractical and the victim must walk out.
This will hurt like fuck-all.
OK. A dislocation means that one of your bones has popped out of its joint. This is usually accompanied by extreme pain and swelling. The five joints most likely to be dislocated are:
Finger: To reduce a finger dislocation, simply pull the affected finger straight out. With about 6 pounds of force, the joint should pop right back in line.
Jaw: A dislocated jaw is very painful, and it will lock up, rendering the victim unable to speak. Explain what you're doing first! Else, you will get bitten. Put on gloves! This will keep the saliva away from any open wounds you might have and prevent Hepatitis B. Wrap your thumbs with some sort of cloth. Place your thumbs on the patient's molars, and grip the lower jaw with your other fingers. Then pull the entire jaw straight out and down. When you clear the bone, just give a quick lateral tug to put the joint back in place!
shoulder: This one is murder, pain-wise. But once the joint's back in place, it will feel 100 times better. Have the victim grasp the opposite shoulder with the hand on the affected side. Slowly pull straight down on the elbow to loosen the muscles - they will have tightened around the dislocation. You want to use about 12 pounds of force for this. This WILL hurt like hell! It has to be done. Once you feel the arm start to loosen, SLOWLY rotate the arm up and away from the body. The joint will roll back into place.
Knee: The knee is rather simple: Pull the lower leg straight out to loosen the muscles, then grab hold of the kneecap and slide it back into place. It should pop right in.
Hip: You have no chance of reducing a hip dislocation in the backcountry. Carry the victim to a hospital - reducing a dislocated hip requires lots of muscle relaxants and painkillers.