<canvas width="600" height="400"></canvas>
<script>
var screen = document.querySelector("canvas");
var pen = screen.getContext("2d");
pen.fillStyle= "green";
pen.fillRect(0,0,600,400)
pen.fillStyle= "red";
pen.fillRect(175,50,90,90)
pen.fillStyle= "red";
pen.fillRect(335,50,90,90)
pen.fillStyle= "red";
pen.fillRect(265,140,70,100)
pen.fillStyle= "red";
pen.fillRect(335,195,70,100)
pen.fillStyle= "red";
pen.fillRect(195,195,70,100)
</script>
