The typical steps for operating a fire extinguisher (described by the acronym "PASS") are the following:
P - Pull the safety pin
A - Aim the nozzle at the base of the fire, from a safe distance (about six feet away)
S - Squeeze the handle
S - Sweep the extinguisher from side to side while aiming at the base of the fire
There are various types of extinguishers, which are used for different types of fires; using the wrong type can worsen the fire hazard, but using the right one can better the situation. Please note: You are not required to fight a fire. Get out or away and call the Fire Department.