Go to My Stuff > My Profiles > then - scroll down to -

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:

Click on "BROWSE", find the picture you want, and upload your avatar.

(Your image must be smaller than 80x80 pixels; .gif, .jpg, .png accepted)