What exactly is my job as the square leg umpire?

You stand at the striker's end, out to the side on the leg side, and back up the main umpire, who stands behind the stumps at the bowler's end. In Stage 1 every over is bowled from the same end, so you stay at the same end all innings.

Your main calls are run outs at the striker's end, and no-balls for fielders in the wrong place (more than two behind square leg, or one within 15 metres of the striker). You also help with things the main umpire can't see well from their end, such as hit wicket, a batter turning for another run without grounding their bat ("one short"), and catches near you.

Wides, other no-balls and boundaries are the main umpire's calls, not yours. Stumpings are never given out in Stage 1. Keep the game safe and flowing, and remember it's about the kids learning and enjoying the game.