I don't believe the confirmation code shows the fare class.

You can find it by looking at your reservation on usairways.com. When you are signed into your account, on the far right of any trips you have booked is a link that says "Details." Click on that, and expand your trip to view any/all segments you have booked on that trip. Under Cabin, it will tell you which class of service (Coach, First, etc), with a letter in parentheses. That letter is your fare class.