Hi Kimberly!
Thank you for bringing your question to the Disney Parks Moms Panel. The Park Hopper option is a great way to maximize your time and options when visiting Walt Disney World Resort!
Since you have already purchased your tickets, to
upgrade them to a Park Hopper you'll need to do this in person during your visit. You'll need to stop by a ticket windows at any of the parks, concierge desk at any Walt Disney World Resort hotel or the Guest Relations location at Disney Springs. The price difference depends on which ticket you currently have, so to check on this ahead of time you'll want to visit the
theme park ticket page. Though pricing is subject to change, based on currently provided information if you have a two day Adult ticket this is currently $199, with the Park Hopper option being an additional $60. For a four day park ticket, the different is $75. Play around with this selection and you should see the options at the bottom to price the difference.
Please let us know if you have any other questions!
-Lindsey ºOº