well, if its a warm-up 10 minutes with a 20 second sprint with 40 second "paddle" (meaning just pulling the handle with no strength)
if you are going to try and make it a short workout, you can do a 2k which took my dad (a non-rower) about 9 minutes,
or you can do 5 minutes on, 3 minutes off for 5 pieces with higher rates (going up and down the slide fatser which there is a number in the top right corner of the screen that shows how many strokes per minute) porbably be around a 27-33.
long workout, you could do 20 minute intervals with 5 minutes off (strokes per minute should be around a 24-26)
if you want me to give you details like the numbers you should be pulling or stuff like that i can help