Organization:
There will be 5:5 or 4:4 with extra players on the sides, the wingers. These 2 players are with the ball owning team.
The wing players may dribble with the ball first.
After a few minutes they have to play immediately.
The players on the sides are not allowed to score.
After 10 minutes or a little less the offside players change.
Remarks:
Players sometimes find it better to keep their own man, than to prevent a goal by stepping in or covering an opponent standing closer to the goal. Let them do it wrong a few times first. Use these situations later to give them directions.
Points of attention:
Do they know how their fellow players stand when they have to defend?
Don't let anyone release his marked man.
Stand between the opponent and the goals.
Have them positioned so that they can see the opponent and the ball.