Moving to Prezi doesn't have to mean abandoning all the hard work you've put into perfecting your PowerPoint slides. That work is still useful, as you can import your PowerPoint into Prezi. This is a good starting point as it allows you to rework your familiar content.
For this recipe you will need to have a PowerPoint presentation on your computer that you can use. If you choose a PowerPoint you are currently using to teach with, this may be of more value, but any PowerPoint will help you complete the steps.