What are the dog park etiquettes?

Try going without him some time, and observing, asking questions. The answers likely will not be definitive but you'll get the gist of it. Explain that you are a new dog owner and you understand that you need to socialize your dog.

The most basic thing is to be sure to clean up after your dog. Failure to do so will make you and your dog very unpopular.

If your dog is young the older dogs will teach it the necessary skills to be part of a pack. It can sometimes look like they're being rough with a pup but it's all part of the socialization process. Don't rush in to protect your dog unless things get out of hand.

Don't let your dog get away with stealing other dog's toys.