<!DOCTYPE html>
<html>
<head></head>
<body>
<canvas id="mycanvas" width="200" height="200"></canvas>
<script>
var canvas = document.getElementById('mycanvas');
var ctx = canvas.getContext('2d');
ctx.fillStyle = 'red';
ctx.fillRect(0, 0, 200, 200);
</script>
</body>
</html>