Where should I stand during play?

Stand level with the batter's popping crease (the line they ground their bat behind), out on the leg side. On a junior ground that's usually about 10 to 20 metres from the stumps.

Being square on to the crease is what lets you judge run outs, so don't drift in front of or behind it. If a fielder blocks your view, move. Stay clear of where the ball is likely to be hit, and never stand between a fielder and the stumps.