Go to the the American Airlines website, aa.com.
Click on the "AAdvantage" link.
Click on "Buy Upgrades." Follow the directions on your screen to purchase an upgrade to first class.
Call AAdvantage Reservations at 1-800-882-8880.
Follow the telephone prompts that allow you to speak with an agent about upgrading your ticket.
Inform the agent that you want to upgrade to first class and allow him to assist you with your request.
At the self-service machine, choose your desired language.
Enter the required flight or credit card information, and swipe your passport or AAdvantage card.
Follow the screen prompts to request a ticket upgrade.