Here I will explane you some basic volleyball rules and at the bottom of text you can find FIVB Official Volleyball Rules.

Scoring
The winning team in a volleyball game is the first to reach 25 points with a winning margin of at least two points. In match play, the victors have to win three out of five games to win the match. The serving team gets the point if the defensive teams hits the ball out of bounds or incurs a violation. The defensive team gets a point if the server cannot get the ball over the net or the offensive team hits the ball out of bounds.

Player Management
Indoor volleyball teams can field up to six players for a match with substitutions possible after each serve. Beach volleyball leagues pit two pairs of players against each other, creating more space on the playing surface. In indoor volleyball, each team rotates clockwise every serve after the opening serve. The minimum number of players a team can field before forfeiting a match is four.

Serving the Ball
The serving player must start behind the end line when sending the ball over the net. Servers can hit the ball overhanded for greater power or underhanded for a longer hang time. The defensive team has to allow the serve an opportunity to get over the net, which means that defenders cannot block or spike the serve.

Hitting the Ball
Every volleyball player knows the adage “bump, set, spike” when it comes to returning the ball to the serving team. Coaches use this adage not only to encourage the best way to get a point but to keep players from hitting the ball more than three times. An individual player cannot hit the ball twice in a row, requiring teams to hit to each other before returning the serve. Volleyball referees count simultaneous contact of the ball between two players as one touch.

Volleyball Violations
Volleyball players need to be careful how they approach the ball and the net to avoid losing points. A volleyball player has to make contact with a flat palm to avoid carrying or throwing the ball while spiking. Players cannot touch the net as the ball is in play to avoid altering the net’s height. Front-line players cannot reach under the net to distract players or make contact with the ball.

For those  who want to know more about  volleyball rules, I recomend this rules:

FIVB Official Volleyball Rules