The display is the least important bit here, it will show what it gets sent on its HDMI port. As august already pointed out, you need to make the computer the screen is connected to show its output in portrait mode. In something like Windows or Ubuntu, you can simply go to the screen settings and select to rotate the screen 90 degrees either clock- or counterclockwise. Or even flip it upside down.
Once that is done, you can just set new screen dimensions in Concerto - instead of 1920x1080 you'd have 1080x1920 and hey presto. You also need some form of image to use as a backdrop, currently the venerable but great looking "BlueSwoosh Neo" is a landscape image.
Then you also need to set up "display areas" in Concerto that match your vertical orientation, by default you get an image, a text field, a date/time field and a ticker field, all laid out in landscape, not portrait.