Getting a good stretch before you start rowing is important. This prevents muscle strain.
When you are ready to start rowing make sure to set a good resistance and remember to keep it light, you have to be able to go for awhile to get a full cardio workout.
Since the idea behind a rowing machine is to simulate rowing a boat, you generally will sit on a bench and, leaning forward, take hold of the provided "oar" handles with both hands. The important thing here is to grip the handles properly. A proper rowing grip is one that is firm, but relaxed.
It is also important to use proper posture and form to avoid back strain. To avoid straining your back, use primarily your leg and hip muscles. Sit straight up and bend forward at your hips. Your elbows should stay close to your body when pulling the oars or handles.
The three main phases of rowing are: the catch, the power stroke, and the recovery. The catch phase is when you move forward on the rower. Your knees are bent and against your chest. Your upper body is leaning slightly forward while still maintaining good posture. Your back isn't hunched over and your head is up.
The power stroke is when you push against the foot pedals and extend your legs while bringing your hands to your upper ab area. Exhale on this part. Lean back "just a lil' bit" to get maximum benefit.
The recovery phase simply involves straightening your arms, bending the knees, and bringing your body forward again. A good rower blends three of these phases into one another in a smooth continuous fashion.
So now you know exactly how to use a rowing machine! To make it more comfortable, add a padded seat and start rowing your way to a beautiful body.