Law 7 - Method of playing (key point is the last one!):
PLAYING A MATCH
A match is started by a kick-off.
After the kick-off, any player who is on-side may take the ball and run with it.
Any player may throw it or kick it.
Any player may give the ball to another player.
Any player may tackle, hold or shove an opponent holding the ball.
Any player may fall on the ball.