html5: Show an image OVER the canvas

I was trying to implement the new html5 canvas tag.

I made a Board for a game using that canvas. Now I wanted to add pawns to the game. I can add an image to canvas using ctx.drawImage() method of canvas, but that actually prints the image on the canvas.

I wanted the pawn to be drawn over the board (theoretically like a layer on it) so that I can move it. I tried this code to add an image using just javascript.

function show_image(src, width, height, alt) {
var img = document.createElement("img");
img.src = src;
img.width = width;
img.height = height;
img.alt = alt;

document.body.appendChild(img);
}

But that didnt help. I can guess that this function just "adds" an element to the body of the main html file and that could be the reason why the image is not shown on the page.

Can anybody help me know how can draw an image over the canvas? Any help will be appreciated!

Feel free to suggest edits.