Great job taking the step in joining a gym! It's totally fun. I'd recommend looking into what group fitness classes the gym offers because they are a nice motivational way to get started with know how to use the equipment and making a group of friends there.
To add on to what dragonwoman said, if you don't plan on showering at the gym, I do sometimes, but not always, but if I'm not I like to take a washcloth with me just to wash my face and arms at the end... feels more refreshing walking home that way.