1. Go to your profile.

2. Click on the button near the top that says EDIT INFO.

3. You should see three boxes. All the way to the right, there should be a box that says "Use my Yahoo! Avatar", and then right beneath a button that says "Edit My Yahoo! Avatar".

4. Click it.

5. It will take you to the link.

OR…

Just type in avatars.yahoo.com in the search bar at the top of your webpage. Make sure you’re logged on. =)

PICTURE AVATAR:

You have to activate your 360 profile. To do that, go to your Yahoo! Answers profile, and then click on the button that says "My 360 profile" in blue letters. It is to the right of your ID. Once you set up the profile, you can click on the button that reads "Edit Personal Photos". That takes you to a page, where you can upload an image you wish to use as your primary photo. After you have added the image, you can set it as your primary. Then, go to your Yahoo! Answers profile, and then click the button that reads "Edit My Info". You will see three boxes down near the bottom toolbar on the page, and the middle one reads "Use my Yahoo! 360 Picture". Check the circle next to it, and then scroll down and save your profile. It will take a short period of time for the picture to process, so be patient. Hope this helped! Good luck!

To get it to show up…

1. Go to your profile

2. Click "Edit My Info"

3. You will be taken to a page where you will see three boxes. One says "No Picture" underneath the box, one says "Use My 360 Picture" underneath the box, and one says "Use My Avatar" underneath the box. Check the circle next to the one that says "Use My Avatar" or next to the one that says "Use My 360 Picture". Whichever one you want.

4. Scroll down.

5. Click "Preview"

6. Click "OK"

7. You’re done.

=)
References :

Then to customize how you look, what outfit to wear.and background + more.

1> Click the “appearance” tab to choose your skin color, face and eyes, and hairstyle. Pick your eye and hair colors by clicking on the colored squares to the right of each image.

2> Click the "apparel" tab You can try on full outfits or different tops and bottoms. Mix and match.

3> Click the “extras" tab to try out accessories like sunglasses. sports and hobbies gear such as backpacks, bikes, and snowboards. Adopt a cute pet. Or try different hats.

4> Click the "Backgrounds" tab if you like the snow, the beach, or a nightclub.

Once you’ve customized your avatar, don’t forget to scroll down to the bottom of the Profile page and press "Preview", and then "OK" in the next screen. And your done.

If you need any help click this link
http://help.yahoo.com/l/us/yahoo/avatars/preferences/index.html
References :