If you want to personalize your gamers with avatar, you can grab Gravatar according to their email.
Gravatar is a service where you can setup you internet globally avatar - on every website where gravatar is used, and you enter one of your gravatar registered emails - you will get as default image same, as you selected on gravatar.
In this demo you will see: - how to load image from gravatar based by email - how to make an button and input without sprites - how to load default image in case gravatar is not found - how to load random image from gravatar if instead of email string is given
(In Google Chrome if you installed extension to make backspace to go back to previous page it may not work properly, then open on "incognito mode").
This demo/example DOESN'T SEND USER EMAIL to web. It makes an md5 first, so only hash is send, which is much safer.