Summarize:

You can access this website on a computer, phone, or tablet. Even if you initially booked your flight through a travel company (such as Expedia or Orbitz), you can still find your flight information on the airline's website.  If you know your flight number and just want to check its estimated arrival or departure time, click the Flight Status link at the top of the page, enter your flight details, and then click the red and white arrow. If it's fewer than 24 hours from takeoff time and you want to check in for your flight, click CHECK-IN in the menu bar at the top of the screen, select an option from the "Find Your Trip By" menu, enter the requested info, and then click the red and white arrow to confirm. You can search for your flight by confirmation number, credit/debit card number, or ticket number. If you received an email confirmation from your flight purchase, you'll find the confirmation number and ticket number in that message. The ticket number is a 13-digit numerical code, while the confirmation number is a 6-digit code made of letters and/or numbers. Enter the name exactly as it was entered at booking time. This displays information about the reservation, including the flight number, departure/arrival times, seating assignments, and upgrades. You'll be prompted to sign in to your American Airlines account if you aren't already signed in. If you don't have an account, you'll be asked to create one. Depending on when and how you bought your ticket, you may be able to modify your seating, meal, and timing preferences.
Navigate to https://www.delta.com/mytrips. Select an option for looking up your flight. Enter the passenger's name and other requested information. Click the FIND MY TRIP button. Follow the on-screen instructions to change your reservation (optional).