Tunturi Rowing machine - strokes per minute

I have a Tunturi rowing machine. I will do approx. 30 strokes per minute at the level 3 or 4 setting. 5'7 female, 124 pounds.

I cannot find any information on what intensity level I should be using or strokes per minute goal.

I am not interested in weight loss, but rather to tone up my body.

Just want to make sure I'm on the right path.