Good news!
The array would indeed make a diagonal line.
What is it you wanted to display? You could have static 'pictures' defined, and every so often switch to a new one. Maybe based on time, maybe when a button is pushed, maybe when a serial message was received. You could have the display slowly scroll left or right, or up & down. Put what else you want displayed in a larger array and read that data out and write it to the display array. Or make up what is being displayed on the fly.