To change your image, you need the desktop version of Yahoo! Messenger. Do you have it? OK, great.
Here’s how to adjust your image if it’s a photo.
To change your avatar, visit http://avatars.yahoo.com/. Sign in (if you haven’t already) and customize – that’s right, customize – your avatar. Your changes are in effect until the next time you feel the urge to make yourself over. Which could be in like five minutes!