When you are ready to see your experience, click on the "Share" button in the upper right corner of the page. Follow the directions and you'll get a URL and a QR code as a way to launch the experience. You'll most likely want the QR code.
Whenever you change anything in your experience, you'll need to "Apply Changes" here before the public-facing experience changes. The QR code and link stay the same, but the experience will include the changes.