Hi
I made an example with comments for you: http://jsfiddle.net/wx0howag/
Feel free to use that code if you want
But I have to warn you that my solution may affect CSS styles on the target site.
That is because it wraps each img with custom div, so strict CSS rules like #someid > img may stop working.
It’s possible to solve the task without wrapping, but then there will be another issue - you have to use absolute positions for buttons in that case, so if user changes size of the window these absolute coordinates should be updated too