Throw-in rules

When the ball goes over the side of the playing field, the area known as touchline, the assistant referee immediately raises his flag to signal that a throw-in must be made. Most leagues follow the FIFA rules for a throw-in:

• The ball must be thrown with both hands.
• It must be thrown from behind the head.
• The player making a throw-in must have both feet on the ground when throwing the ball.
• He may run to gain momentum for the throw-in but both his feet should be on the ground when the ball is released.
• He must stay off the field of play, though he may step on the line when making the throw.
• He can only touch the ball again after it has been played by another player.
• Players must be at least two meters away from the thrower before the ball is released.
• A goal cannot be scored directly from a throw-in. It must be touched first by another player.
• If a player throws the ball into the opponents’ goal, play will be restarted by a goal kick from the opposing team’s end.
• If the throwing player puts the ball into his own team’s goal, play will be restarted with a corner kick for the opposing team.
• A player cannot be offside in football when receiving a throw-in.

source : http://www.football-bible.com/soccer-info/soccer-throw-in.html