Step 1: Don't Panic. Like, Seriously, Don't Panic. You're going to need a clear head for this.
Step 2: Locate the fire extinguisher. It's that big, red thing with a hose and a handle. No, not the firehose, the other one.
Step 3: Pull the pin, turn the handle, and... well, you know, it's not like it's rocket science or anything. Just point it at the fire and... when things get hairy.
1. Don't try to fight the fire with your bare hands. Unless you're a trained firefighter, in which case, go ahead.
2. Keep a 5-foot clear radius around the fire at all times. Any less and you're basically asking to be a crispy critter.
If you need help, call this number: 1-800-FIRE-911. No, seriously, don't, that's just a placeholder.