如何在图像CSS上放置一个思想气泡

I have a work project that entails getting an image from a user, and based on that image, place a thought bubble, or speech bubble on top of that image.I have to consider placement and all that, but I just want a working version first. I'm using the jQuery facial recognition library for the image but I can't find any info on how to get a bubble on the image. I have a work project that entails getting an i