Where must I stand when I'm not bowling, and what is "possession of the rink"?

From laws 12 and 13 of the Laws of the Sport of Bowls (Crystal Mark 4th edition):

Possession of the rink belongs to the player or team whose bowl is being played. It passes to the opponents as soon as each bowl comes to rest, after time to mark a toucher. You may not deliver until the previous bowl has stopped and possession has passed to you.

Positions:

• At the mat end, players not delivering must stand at least 1 metre behind the mat.
• At the head end, players not controlling play stand behind the jack (and away from the head if their side is not in possession). If the jack is in the ditch, stand on the surrounds of the green.
• A player directing play from level with or in front of the jack must move back as soon as the bowl is delivered.
• Never walk into a neighbouring rink where play is in progress, or along any neighbouring rink while an opponent is about to bowl.

Penalty: if you bowl before the previous bowl stops, or distract or interfere with the players in possession, the umpire warns you the first time (in front of your skip). On every later occasion your side's last bowl is declared dead, and if it disturbed the head the opposing skip chooses to replace the head, leave it, or declare the end dead.