There are a few ways you can do this.
Do the math yourself, if possible. You already know the dimensions of your image. If you know the dimensions of the div, you can just put the image at (div width - image width - 10, div height - image height - 10).
Use Javascript to do the heavy lifting for you. Pretty much the same method as above, except you don't need to know the dimensions of the div itself. Javascript can tell you.
A more hackish way would be to put a 10px transparent border around the top and right of your image, and set the position to top right.
