Displaying the avatar in the header is somewhat tricky, and there isn't really a dead set way of doing because of the complexity involved. Basically it involves either editing the header of your website using the custom scripting options for the header, or altering the login/welcome line by using the content templates of your website. Both will require that you have some knowledge of both html, css, and the Spruz SPI language that can be found here: http://my.spruz.com/pt/SPL-Flat-Data-Codes/wiki.htm
Keep in mind that when altering the custom scripting for your header area of the website, you will in turn eliminate the text and content of your header, and you'll have to re-create that as well.
