To do chest presses sit in the same seat you'd use for leg presses -- the right-hand station as you face the machine. Grasp the press arm handles and push, with your palms facing either down or in. Keep your back in contact with the bench seat's padding throughout the exercise.
To do flyes with the butterfly arms, sit in the other station and place one forearm on each of the butterfly arm's padded vertical bars, palms facing forward. Squeeze the two "wings" of the butterfly station together in front of your chest, then relax back to the starting position.
Back and Shoulder Exercises
The high and low pulleys on the Weider Pro 4250 allow you to do a number of back and shoulder exercises. For example, clip a long handle to the high pulley, straddle the seat on that station and pull the bar down to your chest for lat pulldowns. Or clip the same handle to the low pulley and stand in front of it. Hinge forward from the hips and hold that position as you pull the bar up to your chest for bent-over rows. You can also stand almost directly over the low pulley and pull the bar up under your chin, close against your body, to do upright rows. Your shoulders should stay low during this exercise as your elbows wing up on either side of your head.
The low pulley is particularly useful for doing arm exercises. Stand directly over the pulley and do biceps curls, holding the bar in a palms-up grip as you curl it up toward your shoulders. Or stand facing the other way and extend the bar straight up overhead, then bend your arms and lower the bar behind your head. Extend your arms again, pressing the bar back up, to complete a repetition of the triceps extension.
The Weider Pro 4250 offers three stations for working your legs. To do the leg press sit down in the seat, plant both feet on the platform, and push. Ensure your knees and toes point the same direction, and that your knees flex no more than 90 degrees as you bend them to complete the repetition.
You can also use the leg lever for both leg extensions and leg curls. To do leg extensions, sit on the edge of the bench and tuck your shins behind the lower padded bar on the leg lever. Straighten your legs against the machine's resistance, then lower them again.
To do leg curls, stand to one side of the leg lever. Place the knee of your near leg against the uppermost padded bar on the leg lever and tuck your calf behind the lower bar. Bend your knee against the machine's resistance.