This plugin enables you to watermark your images, by placing a simple, yet very customizable watermark beneath the original images (much like the 9GAG
You can see the attachment ids simply by going to yoursite/wp-admin/upload.php and hovering over the images. It's the number right after the attachment_id parameter.
In this case, I'm sorry to say, but you will have to do this by yourself. You should have read that VERY IMPORTANT note :(
I would happily help you, but as my time is limited and precious, I cannot do that for free anymore.