A "radio" button is the round open circle you click on to turn dark and indicate a selected choice as "OK"http://en.wikipedia.org/wiki/Radio_button
As shown on your "My Profile Page":
There may be multiple choices below for specifying your image. If you are changing your current image, select the radio
button next to the option you are using to change your image.
Your current avatar:
O I no longer want to have an avatar.O
URL to your avatar ________________________
(Your image must be smaller than 80x80 pixels; .gif, .jpg, .png accepted) CHECK THE CIRCLE AND PASTE IN YOUR URL TO THE AVATAR YOU WISH TO USE
O Use a stock avatar.