Log back in to the ticket website. Where you first clicked the “Order Tickets” button should now have a “View Tickets” option beside it where you should be able to see the PDF file containing however many tickets you originally ordered.
Try logging in to the ticket website and viewing your tickets from a different browser (i.e. if you are using Safari, try with Firefox or Internet Explorer). If you continue to have issues viewing the file, try logging in from a different computer.