Well, you do have very little information to go on, so maybe consider adding more the next time you post. Things like your likes, and what toys you have....
As for some tasks, since it's a change room, nudity wouldn't be too unusual, so try to be naked as much as possible. Judge how the other guys are, and cover up with a small towel if it's the more polite thing to do.
Choose the shower that has the most traffic past it.
Wear as little as possible clothes when you leave, preferably just a pair of shorts.
Enjoy.