The image I used as an example is a square 32x32px!! of course you can change the image with a differnet size, just change the "background-image: url(" WITH YOUR URL HERE!! ");" but, preferably, keep it tiny!
Please take note that the padding should be the same width as your image or it will be under your name!! also the "margin-top" and "margin-bottom" should be the same height as your image, or it will be decentred!!
If your Username seems tiny next to it, or you just want to make it smaller or bigger, you can change the Username text with this next code:
In this example your username size will be 25 pixels! feel free to edit it to get your desired size!