Different people take coaching in different ways. Some like it because their kid will be on the team, helping out, or even just because they have nothing else to do. Leagues really appreciate it when parents just step up and coach when they can't find anyone. When some people step it up to be a coach, they really don't know what coaching is all about. Also, never yell or get mad a coach if they do something wrong unless you've been a coach because it's a lot harder than it seems coaching a group of kids onto victory. If you still need help coaching and what you're supposed to do, you can also get a volleyball coaching strategies video to help you out. These videos will help you decided which way to run your team and the best way to win many games too!
However, if you still need some help after watching a volleyball coaching strategies video, you may want to go to volleyball coaching clinics. At the clinics, they will explain to you all the rules and things you should and shouldn't do as a coach. Also, since you're a coach, you need to have a volleyball coaching philosophy. This could be either you play to win or play to have fun, etc. The choice is yours how to run the team!