Your question is so fundamental, it's surprising that it's difficult to provide a ready answer.
Maybe Bicycling has something on their web-site. There's been some discussion here, in other threads, but I couldn't tell you what to search for. Almost any general cycling book has a section on riding with groups, and always touch on skills and expected behaviour... etiquette.
To practice your skills and learn more, club rides are good. For learning, you'd be better off with a small group at a recreational pace. And different groups have slightly different expectations, but knowing the basics will get you through in any group.