If the upload didn't work (which it didn't in your case, that's why it's not showing anything), it's probably because the image was too large. You should see something like this near the upload box:

The maximum size of your custom image is 85 by 85 pixels or 488.3 KB (whichever is smaller).

Your image needs to fall within those specifications in order to upload it and use it as an avatar. In other words, it needs to be a very small image.