Mi solucion del ejercicio:
<meta charset="utf-8">
<canvas width="350" height="300"></canvas>
<script>
let pantalla=document.querySelector("canvas");
let pincel = pantalla.getContext("2d");
console.log(pincel);
pincel.fillStyle="darkgreen";
pincel.fillRect(0,0,350,300);
//ojos
pincel.fillStyle="black";
pincel.fillRect(50,50,90,90);
pincel.fillStyle="black";
pincel.fillRect(210,50,90,90);
//nariz
pincel.fillStyle="black";
pincel.fillRect(140,140,70,100);
//boca
pincel.fillStyle="black";
pincel.fillRect(100,190,40,110);
pincel.fillStyle="black";
pincel.fillRect(210,190,40,110);
</script>
