Fiz assim bem centralizado!!
i<canvas width="600" height="400"></canvas>
<script>
var tela=document.querySelector("canvas");
var pincel= tela.getContext("2d");
pincel.fillStyle ="lightgray";
pincel.fillRect(0,0,600,400);
//cabeça
pincel.fillStyle ="darkgreen";
pincel.fillRect(125,50,350,300);
//2
pincel.fillStyle ="black";
pincel.fillRect(180,100,90,90);
//3
pincel.fillStyle ="black";
pincel.fillRect(340,100,90,90);
//4
pincel.fillStyle ="black";
pincel.fillRect(270,190,70,100);
//5
pincel.fillStyle ="black";
pincel.fillRect(230,240,40,110);
//6
pincel.fillStyle ="black";
pincel.fillRect(340,240,40,110);
</script>
