Marketing
Marketing campaigns help increasing the number of guests in your park. To start a marketing campaign open the stats window and check the "Marketing Campaign"-checkbox. You can choose between 3 different campaigns: online, print and TV. The more expensive a campaign is, the more guests will be attracted.
Marketing campaigns start the next day after you checked the checkbox - but only if you have enough money! Take a look into the stats window - if you've paid for it, the campaign is running. If you uncheck the checkbox, the marketing-effect stops immediately.