Option 1: Use one of our shared templates. They generally print 4 to a 8.5×11 page. Then cut.
Option 2: Download one of our templates and upload/take it to a print shop (Vistaprint, Staples, The UPS Store, FedEx Office, etc.) Check out this Google Search for “Postcard Printing”. Many of these services do other sizes besides 4 to a page.