This video explains the basics of how to use a frie extinguisher.
If you encounter a small fire that you feel you can safely put out with a fire extinguisher, make sure you have a safe way to exit behind you and that someone else is calling 911. If the room is too smoky just get out of the building and call 911.
When using a fire extinguisher, remember the PASS method. Pull, Aim, Squeeze, Sweep.
Even after putting out a fire, it is still important to have the fire department come to make sure the fire is completely out and make sure no one is injured.