If you want to learn more about a specific machine or how to do an exercise you see someone doing in the gym, ask a trainer to show you. They are there to help you. Don’t just attempt a movement without consulting someone who can demonstrate the proper form. Safety first; you could hurt yourself even if you’re a regular at the gym. Secondly, you won’t benefit from the exercise unless your form is right.
I know you’re concerned the trainers will try to persuade you into a package of 8 sessions to get you familiar with the equipment. Just be straight, tell them you’re not interested, but you would really appreciate their help with this one machine. Your safety is primary in their mind so they will be happy to help.