I did a quick google of "gym machine tutorials" and "exercise equipment tutorials" and found some stuff that is helpful, but in order to get the really specific information you need you kinda have to google the equipment itself, i.e. "elliptical machine" or "brand x abduction machine" tutorials. Even then, lots of this stuff today is digital and requires a knowledge of how the software and settings work also.
My old gym had a 3 day training period that was mandatory before they let you loose on the machines by yourself (for liability, so you didn't get hurt setting weights too high etc). It was SO helpful to have someone walk me through how to adjust each machine to my height and size as well as resistance levels, and I really don't think I could have figured out how to do even half that stuff properly without it.
Your best bet is gonna be to figure out how not to be embarrassed instead of figuring out the machines on your own. Someone knowledgeable will not only keep you safe with proper form and settings but would also be able to recommend the best approach for YOU as an individual. Asking for help is not a weakness, that is what they are there for and your health and wellbeing are much more important than worrying what some strangers think anyway
If you can't bring yourself to ask for help, I would suggest that you do some recon-go for the treadmill but make mental notes as to the brands/types of machines you think you might be interested in trying, so that you can get specific instructions. There will also be lots of folks here willing to explain what they know if they are familiar with that particular type