99.9% chance it's a spinnaker. There is a ton of information about flying spinnakers online, both in print and on youtube, or you can just go to a book store and buy something like this:
Amazon.com: Sailing For Dummies (9780471791430): J. J. Isler, Peter Isler: Books
and see chapter 12
. Then, find a friend, aquaintance, or experience dock neighbor to take you out, help set up your boat (or go out on theirs), and show you how to fly your chute. You might also want to fly a smaller jib at first if it's blowing any more than 8-10 kts. The loads on the sails will be much higher than you're used to. Keep your fingers out of the winches. At 33-34' feet, you have to be a bit more respectful of the forces involved.