Achieving a flatter midsection isn't possible with a weak upper body. Lats are the biggest muscle in the upper half, so strengthening this area will help you burn more above the waist. Lat pull-downs are also a good one to add.
Securely set the pin on the desired weight.
Stand on the side platforms and hold on to the outer handles. Lift one knee and place it on the padded knee rest. Tightly hold on to the handles as you place your second knee onto the knee rest, and be prepared to hold yourself up (with the assistance of the counterweight). Keep your abs engaged, spine neutral, and shoulders pressed down and back.
Pull yourself up as far as possible, making sure to keep your abs engaged and your shoulders pressed down and back. Slowly release down until your arms are almost straight.
Repeat 10 to 15 times. When getting off of the machine, be sure to pull yourself all the way to the top first. Keeping your arms engaged, slowly lift one knee and lower it to the side platform, then the other.