How do I output the computed distance from the camera on to the dash board?
On the robot, put the value into a SmartDashboard variable with a name you like. Use the SD Write Number function.
On the Dashboard, create a numeric indicator with its label set to the same name you chose before. On the front panel, place the indicator in the Operations tab along with the existing example checkboxes and slider. On the block diagram, it sits outside the main While loop, disconnected from everything else. The Dashboard program contains code that will automatically update the indicator from the SmartDashboard variable.