One of the most popular but practically worthless pieces of gym equipment is the adductor/abductor (inner/outer thigh) machine. It is popular because people still believe that you can spot reduce (get rid of body fat in one specific area). It is ineffective because these muscles do not need strengthening in a seated position. It can also put stress on the lower back and hips, especially if you load up the weights.
Squats and lunges are a much better alternative for working the legs and hips. If you want to isolate the inner/outer thigh muscles, attach a cable strap or resistance band to your ankle.
To work the inner thigh, stand with your working leg close to the attachment, keep the standing leg slightly bent, and move the working leg across your body.
To target the outer thigh turn the other way and move your working leg away from your body. Always keep the standing leg slightly bent, and move the working leg smoothly.
If you are unable to give up the machine keep the range of motion comfortable, select only enough weight that allows you to move the pads smoothly, and keep your back against the pads of the machine.