Create a Hotwire account. In the upper right hand of the Hotwire home screen click on "my account" and follow the instructions.
Book your trip. Once you have an account, you can book your airline trip. Any trip that you purchase will be saved allowing you to look up that trip's details at a later date.
Look up your flight itinerary. Once you have booked a trip on Hotwire, click on the "my account" button. Click on "trip history" and you can print out the itinerary of current and past trips.
