To draw a circle on a HTML canvas, you can use the `arc()` method. Here is some code, which may provide you an understanding of how it works:

```javascript
const canvas = document.getElementById('canvas'); // note that you will have to use your own canvas
const context = canvas.getContext('2d');
const x = 100; // x-coordinate, you can set it up
const y = 100; // y-coordinate, you can set it up too
const radius = 50; // radius of the circle, set-up-able
const color = 'red'; // color of the circle, also set-up-able
context.beginPath();
context.arc(x, y, radius, 0, 2 * Math.PI, false);
context.fillStyle = color;
context.fill();
```

I hope this helps! I also put some comments there, so you can see where and what to edit. Good luck programming!
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