Free Kicks are Footy's version of penalties, and while no one actually gets sent of in the professional game, some leagues ahve there own Red/Yellow card system or sin bin.
Footy may look at first like there is know rules and you can go around wacking people as you please but this is not the case....read on to learn a few of the rules you MUST obey or the man in white (umpire) will have something to say! Of course we could go in deeper here but this will get you moving for now...

Free Kick Definitions

A free kick is given against the player in possession of the of the ball who:
(a) Not disposing of the ball within a reasonable time when held by an opponent.
(b) Not disposing of the ball correctly by using a handball or a kick.
(c) Kicking the ball over the boundary line without it bouncing first or being touched by another player.
(d) Deliberately forcing or taking the ball over the boundary line.
(e) Running more than 15 meters without bouncing the ball or touching the ball on the ground.

A free kick is given against any player who:
(a) Grabs the opponent with the ball above the shoulder or below the knees.
(b) Pushes an opponent in the back.
(c) Trips or attempts to trip an opponent.
(d) Charges an opponent.
(e) Interferes with an opponent attempting to mark in the air by punching or bumping.
(f) Shepherds an opponent when the ball is more than 5 meters away.
(g) Enters the center square before the ball is bounced at the restart of play.

Note: A player who is infringed upon, immediately following the disposal of the ball, may have a fellow team-mate take the free kick from the spot where the ball landed after being disposed of. This is at the umpires adjudication.