Sign up as a Mileage Plus member with United Airlines. You will need your Mileage Plus number to reserve seats online. This will also allow you to accumulate award miles with the airline.
Reserve a seat when you purchase your ticket online. United Airline's website offers a real-time seat map for its flights. Click on the "view seat map" option on the flight's search page. When you have selected your flights, go to the review page and click "select seats" to confirm your reservation.
Log in to the "My Itineraries" section of the website and enter your mileage plus number if you want to reserve seats after you have booked flights. Select "view/modify" for your trip and then click on "seat assignment." You will then be offered a seat map showing your current seat assignment. You can then click on another seat on the map to indicate your preference and then close the seat map to save your reservation.
If you booked through another website or travel agent, have them add your Mileage Plus number to your reservation and you will be able to amend online via "My Itineraries."
Use the Easy Check-in Online facility to reserve a seat prior to departure. This is only available in the 24 hours before your flight is due.
Wait until 329 days before you travel to select a seat. You will not be able to reserve seats on bookings further in advance than this.
