A trip to Florida, eh?"Ticketless" just means they won't send you a ticket in the mail like they used to in the olden days.  Now, you just go there and you can get your boarding pass printed at the airport.  If you're checking luggage (free on Southwest, ain't that right?) you can get the boarding pass at the Southwest desk.  If you have nothing to check, you can get your boarding pass from the desk or from an airline kiosk.  At the kiosk, you can use a credit card to confirm your identity (it doesn't charge your card).Otherwise, you'll just need your driver's license/ID.  That will get you through security. 

You'll also probably want the credit card that you used to buy the ticket – a lot of times you can print your bording pass or check luggage at a kiosk – and the credit card is tied to your ticket record.