How do I upload a desktop Prezi presentation to Prezi online?

My new computer won’t run the Prezi app. Can I upload my presentations ( files) to

Hello @Steven_Taylor, could you please specify if you are on Mac or Windows?

What is happening exactly when you try to run the Prezi Application? Are you talking about Prezi Classic or Prezi Present?

Could you please also let me know the extension of your files?