On a turn, you either draw two parade float cards from the deck or discard parade float cards to claim a route between two locations by placing your ghost trains on it.
For the latter option, you must discard cards matching the color and number of spaces on that route (e.g., two yellow cards for a yellow route that's two spaces long).
If you connect the two locations shown on a ticket with a path of your trains, reveal the ticket, place it face up in front of you, then draw a new ticket.
(If you can't connect locations on either ticket because the paths are blocked, you can take your entire turn to discard those tickets and draw two new ones.)
If you create a route all the way from the Dark Forest region to the Seashore region, you collect the "trick or treat" bonus.