Sending the VISA to VAC office

I was applying for a tourist VISA. Now I got a request to submit it to the NY or LA office. But i am a little lost about the pre-paid airway bill. I live in Dallas. I was thinking of mailing it to LA office.

The website states:

Step 2: Decide how you want your passport returned to you. You can choose to retrieve your passport in person or have your passport delivered to you at home. If you choose to have it delivered, you must include a pre-paid Air Waybill when you submit your passport to the VAC. The VAC will send your passport to the Visa Office and provide you with a tracking number so you can track where your passport is. The fee for the Passport delivery / e-Application service is $34.10.

I have never done this before, this prepaid air-way bill thing, so can anyone tell me what to do here? Does FedEx/UPS have features to send in the $34.10? Any help would be appreciated.